Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/01/16


AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
832 PM PDT THU JUN 30 2016 .SYNOPSIS... Strengthening onshore flow and deepening marine layer will bring cooling trend into weekend. Marine layer clouds will reach into the valleys, however warm and dry conditions will prevail in the mountains and deserts. A gradual warmup is expected early next week as high pressure builds in over the desert Southwest. && .SHORT TERM...(TONIGHT-SUN) A weak upper level trough along the west coast will continue strengthen the onshore flow and deepen the marine layer through the weekend. Current satellite imagery showing low clouds and fog returning to portions of the Central Coast and LA County coast this evening. 00z Vandenberg sounding showing marine layer depth around 1700 feet while ACARS sounding showing marine layer depth around 1200 feet this evening across LA Basin. Marine layer depth expected to increase to around 2000 feet by Friday morning, with little change through the weekend. As a result, looking for marine layer clouds to spread well into the valleys each morning. Mild temperatures expected through the weekend, with warmest valley locations climbing to between 85 and 90 degrees. LAX-Daggett gradient peaked at +6.3 mb this afternoon and is likely to strengthen to around + 8 mb each afternoon through Sunday. As a result, gusty onshore winds will affect the mountains and Antelope Valley each afternoon and evening, The combination of gusty onshore winds and low humidities will bring elevated fire danger for the mountains, deserts, and interior valleys through the weekend. For more details on fire danger including projected weather near the Pines Fire, please see fire section below. .LONG TERM...(MON-THU) Nothing too exciting through the middle of next week either. GFS has definitely slowed down the westward expansion of the desert high pressure dome from a few days ago. The result for now looking more like a very gradual warmup through the middle of next week and no threat of monsoon moisture. Marine lyr will still play a big role in the weather for coastal areas for the forseeable future. && .AVIATION...01/0130Z... At 00Z at KLAX... The inversion was about 1300 feet deep. The top of the inversion was near 4300 feet with a temperature of about 27 degrees Celsius. Overall...Moderate confidence with 00z tafs. S of Point Conception...confidence is good with timing of marine layer returning with higher IFR/low MVFR cigs beginning within +/- 1 hour of tafs. Similar timing for scouring out cigs along coastal tafs Fri morning. 30 percent chance that cigs could linger an additional 2 hours along coastal taf sites. N of Point Conception. Higher confidence with mainly IFR cigs but could see brief moments of MVFR cigs by 15-17z Fri before scouring out. 30 percent chance that cigs could linger a few more hours than tafs represent along coast. KLAX... Moderate confidence in the 00z TAF. Confidence is a bit shaky with the timing that IFR/MVFR cigs will move in this evening. But should be within a couple hours of taf. Also, similar situation for scouring out times in the late morning. There is a 30 percent chance that cigs could linger a few hours longer than 00z taf shows. KBUR... Moderate confidence in the 00z TAF. The uncertainty is due to the timing and if the cigs will make it to KBUR. But chances are better tonight as the marine layer should deepen. The deeper marine layer stratus will also result in a slightly delayed scour out time tomorrow morning but KBUR will be VFR by late morning. && .MARINE...30/200 PM... Overall... Small Craft Advisory winds will continue across the outer waters through the overnight hours tonight. Steep combined seas of 7 to 10 feet across the outer waters will slowly subside tonight as well. Winds and seas across all coastal waters will remain below advisory levels from Friday morning through the weekend. Patchy dense fog will continue across the coastal waters into at least the weekend. && .FIRE WEATHER... 30/815 PM. Elevated fire danger will continue across the mountains, deserts, and interior valleys through the weekend due to combination of gusty onshore winds, warm temperatures, and low humidities. The Pines Fire which is burning in the mountains of Ventura county will be vulnerable to minimum humidities each day between 10 and 15 percent, possibly reaching single digits over the weekend. In addition, there will be poor humidity recoveries at night. Gusty onshore winds will impact the fire area each afternoon. There is the potential for vertical smoke plume growth once again during the afternoon hours on Friday due to ample daytime heating and instability in the atmosphere combined with the very dry fuels. Meanwhile, gusty onshore winds of 25 to 40 mph will be common across the mountains, Antelope Valley, and interior valleys during the afternoon and evening hours through the weekend. Isolated gusts as high as 50 mph can be expected in the foothills of the Antelope Valley near Lake Palmdale. Datyime humidites in the single digits and teens can be expected in the mountains and Antelope Valley, bringing the potential for brief critical fire weather conditions each day. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Friday evening For zones 40-41-87. (See LAXCFWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Friday For zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Gomberg/MW FIRE...Gomberg AVIATION...CK MARINE...KJ SYNOPSIS...Gomberg weather.gov/losangeles Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 909 PM CDT THU JUN 30 2016 .UPDATE... 909 PM CDT THE MAIN UPDATES THIS EVENING WAS TO TRIM THUNDER CHANCES TONIGHT. WATER VAPOR Imagery THIS EVENING SHOWS A WELL DEFINED UPPER-LEVEL IMPULSE DIGGING EAST-SOUTHEASTWARD OVER THE UPPER MISSISSIPPI VALLEY. AN ASSOCIATED STRENGTHENING NORTHWESTERLY UPPER-LEVEL JET (~90 KT) IS EXPECTED TO NOSE INTO NORTHERN ILLINOIS LATE THIS EVENING AND INTO THE OVERNIGHT HOURS...WHICH LOOKS TO PLACE THE AREA IN THE FAVORABLE LEFT EXIT REGION OF THIS UPPER JET. BECAUSE OF THIS...IT APPEARS LIKELY THAT SHOWERS WILL CONTINUE TO FESTER OVER THE AREA LATER THIS EVENING THROUGH THE EARLY MORNING HOURS. WHILE AN ISOLATED LIGHTENING STRIKE OR TWO CANT BE RULED OUT...IT APPEARS THE BEST CHANCE OF THIS WOULD BE WEST OF I-39 IN CLOSER PROXIMITY TO INSTABILITY AXIS. SOME OF THE LATEST AMDAR SOUNDINGS OUT OF KMDW INDICATE VERY LITTLE TO NO INSTABILITY OVER NORTHEASTERN ILLINOIS...SO WE HAVE DROPPED THE THUNDER THREAT OVER THIS AREA...GOING WITH JUST SHOWER WORDING. THE SURFACE COLD FRONT WILL GRADUALLY SHIFT OVER THE AREA OVERNIGHT...WITH WINDS BECOMING NORTHERLY BY DAYBREAK. SOME LOWER CLOUDS COULD MOVE OVER THE AREA BY EARLY MORNING IN THE WAKE OF THIS FRONT...BUT THESE CLOUDS WOULD LIKELY GRADUALLY DIMINISH FRIDAY AFTERNOON. KJB && .SHORT TERM... 234 PM CDT Through Friday... Lead impulse with decaying convection looks to perhaps bring some light showers to far southern portions of the CWA rest of this afternoon. Otherwise, attention will be focused to the northwest on the developing convection over IA this afternoon in advance of sharp mid-upper level trough digging into the upper Mississippi Valley. Debris cloudiness over much of the CWA in association with the decaying convection is limiting instability, though some late day clearing could allow for some modest destabilization over our western CWA. Deep layer shear on the order of 30-40kt could be enough to support a marginal severe wind/hail risk despite MLCAPE of less than 1000 j/kg. Better threat of a stronger storm is west of our CWA, where more sfc heating is taking place this afternoon. Even with the weak and weakening instability as the evening wears on, still think the magnitude of the forcing with the strong trough could be enough to allow showers and isolated thunderstorms to march across much of the CWA. Weak pre-frontal trough should shift winds to the northwest behind the convection, but more substantial synoptic cold front will come charging down the lake late after midnight with a wind shift to north. Though expect the lake to get involved, probably leading to an acceleration of the front down the lake with winds near the lake probably veering a bit more northeasterly with a period of gusts of 30+ mph possible late tonight/early Friday near the lake. Some post-frontal stratocumulus appears likely, perhaps enhanced a bit from the lake before land-lake stability flips in the afternoon and skies clear over the lake and behind the expected afternoon lake breeze. Izzi && .LONG TERM... 246 PM CDT Friday night through Thursday... Friday night through Thursday... To start out the period, strong upper level ridging will be in place across the Northern Rockies and Canadian Rockies with northwest flow into the Great Lakes. At the surface, high pressure will be centered directly over northern Illinois and northwest Indiana providing favorable conditions for radiational cooling with clear skies and very light/calm winds. Expect overnight lows to bottom out near 50 in some of the typical low lying cool spots of the CWA while the Chicago Metro area holds onto mid to upper 50s. Quiet weather along with seasonably cool conditions will continue through the day Saturday under the influence of the high. Light flow will allow an afternoon lake breeze to develop. Temperatures inland should top out in the mid to upper 70s while immediately along the lake front we will only see low to mid 70s. Meanwhile, over the weekend, the baroclinic zone is expected to serve as the focus for convection from the Central Plains east across the Mid-Mississippi Valley. Models continue to struggle with the evolution of a wave that is progged to develop along the baroclinic zone Sunday into Monday, though have in general been trending north with the axis of heavy precip over the past couple days. Central and southern Illinois still appear more favored to see strong thunderstorms with the potential for heavy rain Sunday into Sunday night though the NAM for instance still tries to bring convection up through roughly the I-80 corridor. Models are struggling with convective feedback and might be over- deepening the surface low along the boundary as well as the northward push of the baroclinic zone. Convective outflow may actually end up reinforcing the surface boundary south and lack of any significant upper level support would not be conducive of the boundary pushing north. Continue to favor a more southerly solution, but given the model spread and uncertainty, will remain conservative and maintain chance PoPs mainly south of the I-80 corridor. Wherever it does end up setting up, NAM/GFS both suggest PWATs of around two inches will be in place along with the threat for heavy rainfall. The region will undergo a warming trend from Tuesday on as the upper ridge slides east to the mid section of the country and low/mid level southwesterly flow develops across the Midwest. Latest GFS and ECMWF continue to suggest we might see low to mid 20C 850mb temps mid to late next week which would support temperatures hotter than currently advertised by the general model consensus blend we use as a starting point. Given uncertainty in convective chances under an increasingly unstable air mass and some run-to-run inconsistency, opted to not make any changes from the blend, but there remains some concern we may see a heat wave locally by late in the week. The 12Z ECMWF continues to call for low to mid 90s Thursday and Friday, but the 00Z run was cooler. Deubelbeiss && .AVIATION... For the 00Z TAFs... Concerns with the forecast for Chicago area TAF sites are 1.) likely showers this evening and the chance for brief thunderstorms and 2.) north-northeast winds late tonight into Friday along with possible MVFR cigs. A cold front is progressing into the region with a large area of showers and some storms in southern Wisconsin ahead of this and more isolated activity into eastern Iowa. Enough forcing should exist in the presence of waning instability to allow the showers to reach the Chicago area airports this evening. Rockford has better potential to see thunder than the other sites, though all airports could see a period of wind gusts over 20 kt from the northwest just ahead of or during the showers. The cold front will move through an hour or two after the showers, turning winds northerly and increasing speeds overnight. At ORD and MDW the wind direction is likely to ease just east of north by daybreak Friday with a more traditional lake wind of northeast setting up in the afternoon. Confidence in speeds over 10 kt for most of the day is high. In addition, behind the wind shift to northerly late tonight there will likely be a period of MVFR cigs especially for Chicago airports. Confidence on how long this will persist is low. MTF && .MARINE... 246 PM CDT A weak frontal trough stretches from an area of low pressure near Hudson Bay across Wisconsin and Iowa this afternoon and is providing modest southerly flow across Lake Michigan this afternoon. The front will push across Lake Michigan this evening and tonight allowing a strong northerly breeze to overspread Lake Michigan. A small craft advisory will be issued for the Indiana and Illinois nearshore waters very early Friday through Friday evening as winds and waves increase. High pressure will build across the region Friday night into Saturday allowing conditions to subside. Lake breezes should be able to develop across the southern end of the lake Saturday afternoon. A weak low is expected to move east along the Ohio Valley early next week resulting in fresh east to northeast flow across southern Lake Michigan. There is quite a bit of variance between models on the strength of the low, though, which means lower confidence in the wind speeds Monday. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014...6 AM Friday TO 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002...6 AM Friday TO MIDNIGHT Saturday. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...5 AM Friday TO 10 PM Friday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...5 AM Friday TO 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
904 PM PDT THU JUN 30 2016 .SYNOPSIS... Strengthening onshore flow and deepening marine layer will bring cooling trend into weekend. Marine layer clouds will reach into the valleys, however warm and dry conditions will prevail in the mountains and deserts. A gradual warmup is expected early next week as high pressure builds in over the desert Southwest. && .SHORT TERM...(TDY-SAT) A weak upper level trough along the west coast will continue strengthen the onshore flow and deepen the marine layer through the weekend. Current satellite imagery showing low clouds and fog returning to portions of the Central Coast and LA County coast this evening. 00z Vandenberg sounding showing marine layer depth around 1700 feet while ACARS sounding showing marine layer depth around 1200 feet this evening across LA Basin. Marine layer depth expected to increase to around 2000 feet by Friday morning, with little change through the weekend. As a result, looking for marine layer clouds to spread well into the valleys each morning. Mild temperatures expected through the weekend, with warmest valley locations climbing to between 85 and 90 degrees. LAX-Daggett gradient peaked at +6.3 mb this afternoon and is likely to strengthen to around + 8 mb each afternoon through Sunday. As a result, gusty onshore winds will affect the mountains and Antelope Valley each afternoon and evening, The combination of gusty onshore winds and low humidities will bring elevated fire danger for the mountains, deserts, and interior valleys through the weekend. For more details on fire danger including projected weather near the Pines Fire, please see fire section below. .LONG TERM...(SUN-WED) Nothing too exciting through the middle of next week either. GFS has definitely slowed down the westward expansion of the desert high pressure dome from a few days ago. The result for now looking more like a very gradual warmup through the middle of next week and no threat of monsoon moisture. Marine lyr will still play a big role in the weather for coastal areas for the forseeable future. && .AVIATION...01/0130Z... At 00Z at KLAX... The inversion was about 1300 feet deep. The top of the inversion was near 4300 feet with a temperature of about 27 degrees Celsius. Overall...Moderate confidence with 00z tafs. S of Point Conception...confidence is good with timing of marine layer returning with higher IFR/low MVFR cigs beginning within +/- 1 hour of tafs. Similar timing for scouring out cigs along coastal tafs Fri morning. 30 percent chance that cigs could linger an additional 2 hours along coastal taf sites. N of Point Conception. Higher confidence with mainly IFR cigs but could see brief moments of MVFR cigs by 15-17z Fri before scouring out. 30 percent chance that cigs could linger a few more hours than tafs represent along coast. KLAX... Moderate confidence in the 00z TAF. Confidence is a bit shaky with the timing that IFR/MVFR cigs will move in this evening, But should be within a couple hours of taf. Also, similar situation for scouring out times in the late morning. There is a 30 percent chance that cigs could linger a few hours longer than 00z taf shows. KBUR... Moderate confidence in the 00z TAF. The uncertainty is due to the timing and if the cigs will make it to KBUR. But chances are better tonight as the marine layer should deepen. The deeper marine layer stratus will also result in a slightly delayed scour out time tomorrow morning but KBUR will be VFR by late morning. && .MARINE...30/900 PM... Overall... Small Craft Advisory winds will continue across the outer waters through the overnight hours tonight. Steep combined seas of 7 to 10 feet across the outer waters will slowly subside tonight as well. Winds and seas across all coastal waters will remain below advisory levels from Friday morning through the weekend. Patchy dense fog will continue across the coastal waters into at least the weekend. && .FIRE WEATHER... 30/815 PM. Elevated fire danger will continue across the mountains, deserts, and interior valleys through the weekend due to combination of gusty onshore winds, warm temperatures, and low humidities. The Pines Fire which is burning in the mountains of Ventura county will be vulnerable to minimum humidities each day between 10 and 15 percent, possibly reaching single digits over the weekend. In addition, there will be poor humidity recoveries at night. Gusty onshore winds will impact the fire area each afternoon. There is the potential for vertical smoke plume growth once again during the afternoon hours on Friday due to ample daytime heating and instability in the atmosphere combined with the very dry fuels. Meanwhile, gusty onshore winds of 25 to 40 mph will be common across the mountains, Antelope Valley, and interior valleys during the afternoon and evening hours through the weekend. Isolated gusts as high as 50 mph can be expected in the foothills of the Antelope Valley near Lake Palmdale. Datyime humidites in the single digits and teens can be expected in the mountains and Antelope Valley, bringing the potential for brief critical fire weather conditions each day. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Friday evening For zones 40-41-87. (See LAXCFWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Friday For zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...Gomberg FIRE...Gomberg AVIATION...CK MARINE...CK SYNOPSIS...Gomberg weather.gov/losangeles Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 334 AM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 306 AM CDT FRI JUL 1 2016 .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. && .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1152 PM CDT Thu Jun 30 2016 Front is sitting right along I-55 and will continue to move east remainder of the night. Convection has diminished over most of the area except for north and south of the TAF sites. So new TAFs will not have any pcpn mentioned except for maybe VCSH. Once front moves through and pcpn ends, skies will be mainly scattered with SC and mid clouds remainder of the night, though MOS guidance showing some MVFR clouds for the next several hours at all sites, likely SC/stratus from this evenings pcpn, combined with light winds and partly cloudy skies. May need to add a TEMPO group at all sites to account for this. Tomorrow should be mostly sunny with cirrus moving in during the afternoon. Light and variable winds will become northwesterly after FROPA, and then northerly through tomorrow. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Auten
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 206 AM CDT FRI JUL 1 2016 .UPDATE... 909 PM CDT THE MAIN UPDATES THIS EVENING WAS TO TRIM THUNDER CHANCES TONIGHT. WATER VAPOR Imagery THIS EVENING SHOWS A WELL DEFINED UPPER-LEVEL IMPULSE DIGGING EAST-SOUTHEASTWARD OVER THE UPPER MISSISSIPPI VALLEY. AN ASSOCIATED STRENGTHENING NORTHWESTERLY UPPER-LEVEL JET (~90 KT) IS EXPECTED TO NOSE INTO NORTHERN ILLINOIS LATE THIS EVENING AND INTO THE OVERNIGHT HOURS...WHICH LOOKS TO PLACE THE AREA IN THE FAVORABLE LEFT EXIT REGION OF THIS UPPER JET. BECAUSE OF THIS...IT APPEARS LIKELY THAT SHOWERS WILL CONTINUE TO FESTER OVER THE AREA LATER THIS EVENING THROUGH THE EARLY MORNING HOURS. WHILE AN ISOLATED LIGHTENING STRIKE OR TWO CANT BE RULED OUT...IT APPEARS THE BEST CHANCE OF THIS WOULD BE WEST OF I-39 IN CLOSER PROXIMITY TO INSTABILITY AXIS. SOME OF THE LATEST AMDAR SOUNDINGS OUT OF KMDW INDICATE VERY LITTLE TO NO INSTABILITY OVER NORTHEASTERN ILLINOIS...SO WE HAVE DROPPED THE THUNDER THREAT OVER THIS AREA...GOING WITH JUST SHOWER WORDING. THE SURFACE COLD FRONT WILL GRADUALLY SHIFT OVER THE AREA OVERNIGHT...WITH WINDS BECOMING NORTHERLY BY DAYBREAK. SOME LOWER CLOUDS COULD MOVE OVER THE AREA BY EARLY MORNING IN THE WAKE OF THIS FRONT...BUT THESE CLOUDS WOULD LIKELY GRADUALLY DIMINISH FRIDAY AFTERNOON. KJB && .SHORT TERM... 234 PM CDT Through Friday... Lead impulse with decaying convection looks to perhaps bring some light showers to far southern portions of the CWA rest of this afternoon. Otherwise, attention will be focused to the northwest on the developing convection over IA this afternoon in advance of sharp mid-upper level trough digging into the upper Mississippi Valley. Debris cloudiness over much of the CWA in association with the decaying convection is limiting instability, though some late day clearing could allow for some modest destabilization over our western CWA. Deep layer shear on the order of 30-40kt could be enough to support a marginal severe wind/hail risk despite MLCAPE of less than 1000 j/kg. Better threat of a stronger storm is west of our CWA, where more sfc heating is taking place this afternoon. Even with the weak and weakening instability as the evening wears on, still think the magnitude of the forcing with the strong trough could be enough to allow showers and isolated thunderstorms to march across much of the CWA. Weak pre-frontal trough should shift winds to the northwest behind the convection, but more substantial synoptic cold front will come charging down the lake late after midnight with a wind shift to north. Though expect the lake to get involved, probably leading to an acceleration of the front down the lake with winds near the lake probably veering a bit more northeasterly with a period of gusts of 30+ mph possible late tonight/early Friday near the lake. Some post-frontal stratocumulus appears likely, perhaps enhanced a bit from the lake before land-lake stability flips in the afternoon and skies clear over the lake and behind the expected afternoon lake breeze. Izzi && .LONG TERM... 246 PM CDT Friday night through Thursday... Friday night through Thursday... To start out the period, strong upper level ridging will be in place across the Northern Rockies and Canadian Rockies with northwest flow into the Great Lakes. At the surface, high pressure will be centered directly over northern Illinois and northwest Indiana providing favorable conditions for radiational cooling with clear skies and very light/calm winds. Expect overnight lows to bottom out near 50 in some of the typical low lying cool spots of the CWA while the Chicago Metro area holds onto mid to upper 50s. Quiet weather along with seasonably cool conditions will continue through the day Saturday under the influence of the high. Light flow will allow an afternoon lake breeze to develop. Temperatures inland should top out in the mid to upper 70s while immediately along the lake front we will only see low to mid 70s. Meanwhile, over the weekend, the baroclinic zone is expected to serve as the focus for convection from the Central Plains east across the Mid-Mississippi Valley. Models continue to struggle with the evolution of a wave that is progged to develop along the baroclinic zone Sunday into Monday, though have in general been trending north with the axis of heavy precip over the past couple days. Central and southern Illinois still appear more favored to see strong thunderstorms with the potential for heavy rain Sunday into Sunday night though the NAM for instance still tries to bring convection up through roughly the I-80 corridor. Models are struggling with convective feedback and might be over- deepening the surface low along the boundary as well as the northward push of the baroclinic zone. Convective outflow may actually end up reinforcing the surface boundary south and lack of any significant upper level support would not be conducive of the boundary pushing north. Continue to favor a more southerly solution, but given the model spread and uncertainty, will remain conservative and maintain chance PoPs mainly south of the I-80 corridor. Wherever it does end up setting up, NAM/GFS both suggest PWATs of around two inches will be in place along with the threat for heavy rainfall. The region will undergo a warming trend from Tuesday on as the upper ridge slides east to the mid section of the country and low/mid level southwesterly flow develops across the Midwest. Latest GFS and ECMWF continue to suggest we might see low to mid 20C 850mb temps mid to late next week which would support temperatures hotter than currently advertised by the general model consensus blend we use as a starting point. Given uncertainty in convective chances under an increasingly unstable air mass and some run-to-run inconsistency, opted to not make any changes from the blend, but there remains some concern we may see a heat wave locally by late in the week. The 12Z ECMWF continues to call for low to mid 90s Thursday and Friday, but the 00Z run was cooler. Deubelbeiss && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014...6 AM Friday TO 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002...6 AM Friday TO MIDNIGHT Saturday. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...5 AM Friday TO 10 PM Friday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...5 AM Friday TO 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO Area Forecast Discussion National Weather Service Lincoln IL 1046 AM CDT FRI JUL 1 2016 .UPDATE... Issued at 1046 AM CDT Fri Jul 1 2016 High pressure will dominate the weather across central Illinois today, providing partly to mostly sunny skies and cool conditions. Current forecast is right on track and requires no updates. && .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 610 AM CDT Fri Jul 1 2016 A band of MVFR with local IFR cigs was just north of the forecast area early this morning and was tracking south at about 15 kts. Main question is whether this band of moisture will mix out by mid-morning or will it be able to make it across at least our northern half of the forecast area. Forecast soundings suggest a period of sct-bkn cigs at BMI and PIA with more of a scattered cloud base of 1500-2500 feet further south. Any bkn cigs should lift to VFR as drier air settles south into the forecast area by this afternoon with VFR conditions continuing into the overnight hours. Surface flow will be northerly today at 8 to 15 kts and light northeasterly tonight with speeds of 3 to 7 kts expected. && .ILX Watches/Warnings/Advisories... NONE. && $$ UPDATE...Barnes SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Smith
  [top] Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 630 AM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 12Z TAFs... 630 am...North/northeast winds will remain in the 10-15kt range through mid afternoon with gusts up to 20kts at times. Higher gusts can be expected near the lake and at gyy. The winds will turn a bit more northeasterly late this afternoon into early this evening as speeds begin to diminish. As high pressure builds across the region tonight...winds will become light and variable and likely calm in many locations. Mvfr cigs will remain sct varying bkn through the morning as they slowly lift to low vfr. Still quite a bit of mvfr cigs across southern WI so opted to maintain prevailing mvfr cigs for this morning. Clouds will eventually scatter out this afternoon into early this evening. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 617 AM CDT FRI JUL 1 2016 .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 610 AM CDT Fri Jul 1 2016 A band of MVFR with local IFR cigs was just north of the forecast area early this morning and was tracking south at about 15 kts. Main question is whether this band of moisture will mix out by mid-morning or will it be able to make it across at least our northern half of the forecast area. Forecast soundings suggest a period of sct-bkn cigs at BMI and PIA with more of a scattered cloud base of 1500-2500 feet further south. Any bkn cigs should lift to VFR as drier air settles south into the forecast area by this afternoon with VFR conditions continuing into the overnight hours. Surface flow will be northely today at 8 to 15 kts and light northeasterly tonight with speeds of 3 to 7 kts expected. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Smith
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 334 AM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 306 AM CDT FRI JUL 1 2016 .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. && .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1152 PM CDT Thu Jun 30 2016 Front is sitting right along I-55 and will continue to move east remainder of the night. Convection has diminished over most of the area except for north and south of the TAF sites. So new TAFs will not have any pcpn mentioned except for maybe VCSH. Once front moves through and pcpn ends, skies will be mainly scattered with SC and mid clouds remainder of the night, though MOS guidance showing some MVFR clouds for the next several hours at all sites, likely SC/stratus from this evenings pcpn, combined with light winds and partly cloudy skies. May need to add a TEMPO group at all sites to account for this. Tomorrow should be mostly sunny with cirrus moving in during the afternoon. Light and variable winds will become northwesterly after FROPA, and then northerly through tomorrow. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Auten
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 206 AM CDT FRI JUL 1 2016 .UPDATE... 909 PM CDT THE MAIN UPDATES THIS EVENING WAS TO TRIM THUNDER CHANCES TONIGHT. WATER VAPOR Imagery THIS EVENING SHOWS A WELL DEFINED UPPER-LEVEL IMPULSE DIGGING EAST-SOUTHEASTWARD OVER THE UPPER MISSISSIPPI VALLEY. AN ASSOCIATED STRENGTHENING NORTHWESTERLY UPPER-LEVEL JET (~90 KT) IS EXPECTED TO NOSE INTO NORTHERN ILLINOIS LATE THIS EVENING AND INTO THE OVERNIGHT HOURS...WHICH LOOKS TO PLACE THE AREA IN THE FAVORABLE LEFT EXIT REGION OF THIS UPPER JET. BECAUSE OF THIS...IT APPEARS LIKELY THAT SHOWERS WILL CONTINUE TO FESTER OVER THE AREA LATER THIS EVENING THROUGH THE EARLY MORNING HOURS. WHILE AN ISOLATED LIGHTENING STRIKE OR TWO CANT BE RULED OUT...IT APPEARS THE BEST CHANCE OF THIS WOULD BE WEST OF I-39 IN CLOSER PROXIMITY TO INSTABILITY AXIS. SOME OF THE LATEST AMDAR SOUNDINGS OUT OF KMDW INDICATE VERY LITTLE TO NO INSTABILITY OVER NORTHEASTERN ILLINOIS...SO WE HAVE DROPPED THE THUNDER THREAT OVER THIS AREA...GOING WITH JUST SHOWER WORDING. THE SURFACE COLD FRONT WILL GRADUALLY SHIFT OVER THE AREA OVERNIGHT...WITH WINDS BECOMING NORTHERLY BY DAYBREAK. SOME LOWER CLOUDS COULD MOVE OVER THE AREA BY EARLY MORNING IN THE WAKE OF THIS FRONT...BUT THESE CLOUDS WOULD LIKELY GRADUALLY DIMINISH FRIDAY AFTERNOON. KJB && .SHORT TERM... 234 PM CDT Through Friday... Lead impulse with decaying convection looks to perhaps bring some light showers to far southern portions of the CWA rest of this afternoon. Otherwise, attention will be focused to the northwest on the developing convection over IA this afternoon in advance of sharp mid-upper level trough digging into the upper Mississippi Valley. Debris cloudiness over much of the CWA in association with the decaying convection is limiting instability, though some late day clearing could allow for some modest destabilization over our western CWA. Deep layer shear on the order of 30-40kt could be enough to support a marginal severe wind/hail risk despite MLCAPE of less than 1000 j/kg. Better threat of a stronger storm is west of our CWA, where more sfc heating is taking place this afternoon. Even with the weak and weakening instability as the evening wears on, still think the magnitude of the forcing with the strong trough could be enough to allow showers and isolated thunderstorms to march across much of the CWA. Weak pre-frontal trough should shift winds to the northwest behind the convection, but more substantial synoptic cold front will come charging down the lake late after midnight with a wind shift to north. Though expect the lake to get involved, probably leading to an acceleration of the front down the lake with winds near the lake probably veering a bit more northeasterly with a period of gusts of 30+ mph possible late tonight/early Friday near the lake. Some post-frontal stratocumulus appears likely, perhaps enhanced a bit from the lake before land-lake stability flips in the afternoon and skies clear over the lake and behind the expected afternoon lake breeze. Izzi && .LONG TERM... 246 PM CDT Friday night through Thursday... Friday night through Thursday... To start out the period, strong upper level ridging will be in place across the Northern Rockies and Canadian Rockies with northwest flow into the Great Lakes. At the surface, high pressure will be centered directly over northern Illinois and northwest Indiana providing favorable conditions for radiational cooling with clear skies and very light/calm winds. Expect overnight lows to bottom out near 50 in some of the typical low lying cool spots of the CWA while the Chicago Metro area holds onto mid to upper 50s. Quiet weather along with seasonably cool conditions will continue through the day Saturday under the influence of the high. Light flow will allow an afternoon lake breeze to develop. Temperatures inland should top out in the mid to upper 70s while immediately along the lake front we will only see low to mid 70s. Meanwhile, over the weekend, the baroclinic zone is expected to serve as the focus for convection from the Central Plains east across the Mid-Mississippi Valley. Models continue to struggle with the evolution of a wave that is progged to develop along the baroclinic zone Sunday into Monday, though have in general been trending north with the axis of heavy precip over the past couple days. Central and southern Illinois still appear more favored to see strong thunderstorms with the potential for heavy rain Sunday into Sunday night though the NAM for instance still tries to bring convection up through roughly the I-80 corridor. Models are struggling with convective feedback and might be over- deepening the surface low along the boundary as well as the northward push of the baroclinic zone. Convective outflow may actually end up reinforcing the surface boundary south and lack of any significant upper level support would not be conducive of the boundary pushing north. Continue to favor a more southerly solution, but given the model spread and uncertainty, will remain conservative and maintain chance PoPs mainly south of the I-80 corridor. Wherever it does end up setting up, NAM/GFS both suggest PWATs of around two inches will be in place along with the threat for heavy rainfall. The region will undergo a warming trend from Tuesday on as the upper ridge slides east to the mid section of the country and low/mid level southwesterly flow develops across the Midwest. Latest GFS and ECMWF continue to suggest we might see low to mid 20C 850mb temps mid to late next week which would support temperatures hotter than currently advertised by the general model consensus blend we use as a starting point. Given uncertainty in convective chances under an increasingly unstable air mass and some run-to-run inconsistency, opted to not make any changes from the blend, but there remains some concern we may see a heat wave locally by late in the week. The 12Z ECMWF continues to call for low to mid 90s Thursday and Friday, but the 00Z run was cooler. Deubelbeiss && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014...6 AM Friday TO 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002...6 AM Friday TO MIDNIGHT Saturday. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...5 AM Friday TO 10 PM Friday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...5 AM Friday TO 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 326 PM CDT FRI JUL 1 2016 .SHORT TERM... 211 PM CDT Through Saturday... High pressure is centered across the eastern Dakotas and Minnesota this afternoon providing fair conditions along with a modest northerly breeze across much of northern Illinois and northwest Indiana. A little bit of a lake shadow can be seen on visible satellite imagery along with some convergence in the winds stretching from the middle of Lake County, IL south across Cook County. Northeast flow in place on the east side of the boundary has kept temperatures in the low to mid 60s immediately along the lake front with mid 70s in place farther inland. Otherwise, it has been a quiet day across the region with some afternoon fair weather cumulus continuing to erode as dry air advects into the region. Expect skies to go mostly clear this evening and tonight once the cumulus dissipates. The high center is progged to build southeast into northern Illinois by the predawn hours and the ridge axis should settle just to our south during the day Saturday. Favorable conditions for radiational cooling will be in place overnight and leaned towards some of the cooler bias corrected guidance to try to hit the typical cold spots in the CWA which should cool to around the 50 mark and wouldn`t be surprised if a couple spots even dipped into the 40s. Most of the Chicago metro and urban heat island area should hold onto mid even upper 50s though. Expect fair conditions to continue through the day Saturday with light flow allowing a lake breeze to develop. Temperatures should warm into the mid to upper 70s with increasing cirrus streaming overhead. Deubelbeiss && .LONG TERM... 311 PM CDT Saturday night through Friday... The main forecast concerns will center around the potential of moderate to heavy rainfall over portions of the area Sunday into Sunday evening. A series of upper level disturbances are expected to track eastward across the Mid-Mississippi valley later in the weekend within a semi- zonal upper-level flow pattern. Model guidance continues to suggest that this will help induce and drive an area of surface low pressure from the Central and Southern Plains across the Mid-Mississippi valley by Sunday evening. All in all this is shaping up to be a impressive rain event for some in Illinois and Indiana as a 40+ KT low-level jet noses into the region by Sunday. With high Precipitable water values up to around 2 inches, heavy rain will certainly be an issue Sunday. The main question, however, continues to be how far north will this rain get into northern Illinois/northwest Indiana. This is especially true given there will be relatively dry easterly flow that will be in place into Sunday as the surface ridge axis gradually shifts over the eastern Great Lakes region. Ultimately this could play havoc in how far north the rain does proceed into Sunday, possibly even resulting in a sharp gradient between areas with rain and areas with little to no rain. In spite of this, the latest 12 UTC guidance has shifted the focus a bit farther north into at least my southern areas (south of I80) Sunday and Sunday evening. If this pans out, it could be a very rainy and cool Sunday across my southern areas, with the potential of 1 to 3 inches of rainfall. Thunderstorms chances look minimal, and likely confined over far southern sections of the area, if not south of the area all together, in closer proximity to the nose of the low-level jet. Following this system it appears that the 4th will be drying out area-wide and could shape up to be a pretty nice day. High temps on the 4th look to be around 80, though onshore flow will result in cooler conditions along the lake. As we head into next week it still appears that a board flat upper level ridge will begin to set up over the CONUS. This should help set the stage for a warming trend through the week as the flow turns southerly again by Tuesday night. The air mass expected to set up over the area looks to support temperatures well into the 80s by mid- week, with some 90s even possible by Thursday and Friday. If this higher heat pans out, we could also be flirting with heat index values near 105. However, I have some concerns that this more extreme heat in the 90s could fail to occur. First, it appears that the flat nature to the upper ridge will favor a potentially active period of weather over the Northern Plains and Upper Midwest and is not out of the question that this could spawn an MCS or two, which could impact the area later in the week, and impact the magnitude of high temperatures. Secondly, it appears that a cold front will be approaching the area by late week, and depending on its timing, (which could depend on the amount of convective activity) it may push through and push the heat to our south. All in all, our current forecast mentions highs near 90, but confidence at this time is a bit lower than average. KJB && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 326 PM CDT The small craft advisory will continue into tonight as northerlywinds continue to produce waves above 4 ft. Conditions will improveon Saturday, however, as a surface ridge of high pressure buildsover the southern part of the lake. Light winds are expected for acouple of days as this high dominates. The only system of interestthis weekend is an area of low pressure, which is expected to tracksouth of the lake Sunday night. This low could result in a period ofmodest easterly winds (~10-20 KT) along southern Lake Michigan. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 311 PM CDT FRI JUL 1 2016 .SHORT TERM... 211 PM CDT Through Saturday... High pressure is centered across the eastern Dakotas and Minnesota this afternoon providing fair conditions along with a modest northerly breeze across much of northern Illinois and northwest Indiana. A little bit of a lake shadow can be seen on visible satellite imagery along with some convergence in the winds stretching from the middle of Lake County, IL south across Cook County. Northeast flow in place on the east side of the boundary has kept temperatures in the low to mid 60s immediately along the lake front with mid 70s in place farther inland. Otherwise, it has been a quiet day across the region with some afternoon fair weather cumulus continuing to erode as dry air advects into the region. Expect skies to go mostly clear this evening and tonight once the cumulus dissipates. The high center is progged to build southeast into northern Illinois by the predawn hours and the ridge axis should settle just to our south during the day Saturday. Favorable conditions for radiational cooling will be in place overnight and leaned towards some of the cooler bias corrected guidance to try to hit the typical cold spots in the CWA which should cool to around the 50 mark and wouldn`t be surprised if a couple spots even dipped into the 40s. Most of the Chicago metro and urban heat island area should hold onto mid even upper 50s though. Expect fair conditions to continue through the day Saturday with light flow allowing a lake breeze to develop. Temperatures should warm into the mid to upper 70s with increasing cirrus streaming overhead. Deubelbeiss && .LONG TERM... 311 PM CDT Saturday night through Friday... The main forecast concerns will center around the potential of moderate to heavy rainfall over portions of the area Sunday into Sunday evening. A series of upper level disturbances are expected to track eastward across the Mid-Mississippi valley later in the weekend within a semi- zonal upper-level flow pattern. Model guidance continues to suggest that this will help induce and drive an area of surface low pressure from the Central and Southern Plains across the Mid-Mississippi valley by Sunday evening. All in all this is shaping up to be a impressive rain event for some in Illinois and Indiana as a 40+ KT low-level jet noses into the region by Sunday. With high Precipitable water values up to around 2 inches, heavy rain will certainly be an issue Sunday. The main question, however, continues to be how far north will this rain get into northern Illinois/northwest Indiana. This is especially true given there will be relatively dry easterly flow that will be in place into Sunday as the surface ridge axis gradually shifts over the eastern Great Lakes region. Ultimately this could play havoc in how far north the rain does proceed into Sunday, possibly even resulting in a sharp gradient between areas with rain and areas with little to no rain. In spite of this, the latest 12 UTC guidance has shifted the focus a bit farther north into at least my southern areas (south of I80) Sunday and Sunday evening. If this pans out, it could be a very rainy and cool Sunday across my southern areas, with the potential of 1 to 3 inches of rainfall. Thunderstorms chances look minimal, and likely confined over far southern sections of the area, if not south of the area all together, in closer proximity to the nose of the low-level jet. Following this system it appears that the 4th will be drying out area-wide and could shape up to be a pretty nice day. High temps on the 4th look to be around 80, though onshore flow will result in cooler conditions along the lake. As we head into next week it still appears that a board flat upper level ridge will begin to set up over the CONUS. This should help set the stage for a warming trend through the week as the flow turns southerly again by Tuesday night. The air mass expected to set up over the area looks to support temperatures well into the 80s by mid- week, with some 90s even possible by Thursday and Friday. If this higher heat pans out, we could also be flirting with heat index values near 105. However, I have some concerns that this more extreme heat in the 90s could fail to occur. First, it appears that the flat nature to the upper ridge will favor a potentially active period of weather over the Northern Plains and Upper Midwest and is not out of the question that this could spawn an MCS or two, which could impact the area later in the week, and impact the magnitude of high temperatures. Secondly, it appears that a cold front will be approaching the area by late week, and depending on its timing, (which could depend on the amount of convective activity) it may push through and push the heat to our south. All in all, our current forecast mentions highs near 90, but confidence at this time is a bit lower than average. KJB && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 311 PM CDT FRI JUL 1 2016 .SHORT TERM... 211 PM CDT Through Saturday... High pressure is centered across the eastern Dakotas and Minnesota this afternoon providing fair conditions along with a modest northerly breeze across much of northern Illinois and northwest Indiana. A little bit of a lake shadow can be seen on visible satellite imagery along with some convergence in the winds stretching from the middle of Lake County, IL south across Cook County. Northeast flow in place on the east side of the boundary has kept temperatures in the low to mid 60s immediately along the lake front with mid 70s in place farther inland. Otherwise, it has been a quiet day across the region with some afternoon fair weather cumulus continuing to erode as dry air advects into the region. Expect skies to go mostly clear this evening and tonight once the cumulus dissipates. The high center is progged to build southeast into northern Illinois by the predawn hours and the ridge axis should settle just to our south during the day Saturday. Favorable conditions for radiational cooling will be in place overnight and leaned towards some of the cooler bias corrected guidance to try to hit the typical cold spots in the CWA which should cool to around the 50 mark and wouldn`t be surprised if a couple spots even dipped into the 40s. Most of the Chicago metro and urban heat island area should hold onto mid even upper 50s though. Expect fair conditions to continue through the day Saturday with light flow allowing a lake breeze to develop. Temperatures should warm into the mid to upper 70s with increasing cirrus streaming overhead. Deubelbeiss && .LONG TERM... 311 PM CDT Saturday night through Friday... The main forecast concerns will center around the potential of moderate to heavy rainfall over portions of the area Sunday into Sunday evening. A series of upper level disturbances are expected to track eastward across the Mid-Mississippi valley later in the weekend within a semi- zonal upper-level flow pattern. Model guidance continues to suggest that this will help induce and drive an area of surface low pressure from the Central and Southern Plains across the Mid-Mississippi valley by Sunday evening. All in all this is shaping up to be a impressive rain event for some in Illinois and Indiana as a 40+ KT low-level jet noses into the region by Sunday. With high Precipitable water values up to around 2 inches, heavy rain will certainly be an issue Sunday. The main question, however, continues to be how far north will this rain get into northern Illinois/northwest Indiana. This is especially true given there will be relatively dry easterly flow that will be in place into Sunday as the surface ridge axis gradually shifts over the eastern Great Lakes region. Ultimately this could play havoc in how far north the rain does proceed into Sunday, possibly even resulting in a sharp gradient between areas with rain and areas with little to no rain. In spite of this, the latest 12 UTC guidance has shifted the focus a bit farther north into at least my southern areas (south of I80) Sunday and Sunday evening. If this pans out, it could be a very rainy and cool Sunday across my southern areas, with the potential of 1 to 3 inches of rainfall. Thunderstorms chances look minimal, and likely confined over far southern sections of the area, if not south of the area all together, in closer proximity to the nose of the low-level jet. Following this system it appears that the 4th will be drying out area-wide and could shape up to be a pretty nice day. High temps on the 4th look to be around 80, though onshore flow will result in cooler conditions along the lake. As we head into next week it still appears that a board flat upper level ridge will begin to set up over the CONUS. This should help set the stage for a warming trend through the week as the flow turns southerly again by Tuesday night. The air mass expected to set up over the area looks to support temperatures well into the 80s by mid- week, with some 90s even possible by Thursday and Friday. If this higher heat pans out, we could also be flirting with heat index values near 105. However, I have some concerns that this more extreme heat in the 90s could fail to occur. First, it appears that the flat nature to the upper ridge will favor a potentially active period of weather over the Northern Plains and Upper Midwest and is not out of the question that this could spawn an MCS or two, which could impact the area later in the week, and impact the magnitude of high temperatures. Secondly, it appears that a cold front will be approaching the area by late week, and depending on its timing, (which could depend on the amount of convective activity) it may push through and push the heat to our south. All in all, our current forecast mentions highs near 90, but confidence at this time is a bit lower than average. KJB && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion National Weather Service Lincoln IL 259 PM CDT FRI JUL 1 2016 .SHORT TERM...(Tonight) ISSUED AT 258 PM CDT Fri Jul 1 2016 1024mb high centered over Minnesota will dominate the weather across central Illinois tonight. Scattered diurnal clouds this afternoon will dissipate toward sunset, followed by clear skies through the evening. High/mid clouds will gradually begin to increase from the southwest overnight, as a frontal boundary extending from southern Kansas to western Tennessee begins to shift back northward. Low temperatures will range from the lower 50s across the NE KILX CWA...to the upper 50s far southwest around Jacksonville. && .LONG TERM...(Saturday through Friday) ISSUED AT 258 PM CDT Fri Jul 1 2016 Main forecast concern of the next several days revolves around precipitation chances/timing and heavy rainfall threat for the long holiday weekend. Saturday is still shaping up to be a pretty nice day across central and southeast Illinois. High pressure and the associated dry airmass will we slow to depart, and the richer/deeper moisture return does not really begin until Saturday night. Low rain chances will begin to spread in from the southwest by late in the day, but don`t expect it to be much more than light rain or sprinkles. Strong WAA/isentropic lift will begin to overspread the area Saturday night ahead of a slow moving short wave coming out of the Plains. This should have showers/storms breaking out across much of the forecast area by morning. Forcing from the upper wave will keep precipitation chances going for much of Sunday, Sunday night, and early Monday. However, it still appears that most of the rain will have pulled away in time for Monday evening fireworks displays. Rainfall through the Saturday night-early Monday period still has the potential to be on the heavy side from time to time, with widespread precipitable water values around 2" for much of the period. However, will continue to hold off on any Flood Watches. The reasons for this include the relatively dry antecedent conditions across the forecast area, the extended period over which the rain will fall, and the significant model spread persisting with the heavy rain axis. However, the flood threat will need to be monitored as the system draws closer. After a period of cooler than normals days with clouds, rain, or northerly winds in the vicinity, warmer weather will build through the rest of the period as upper level heights rise. However, the developing ridging will be pretty flat, with periodic disturbances in our vicinity. This results in an extended period of low PoPs, despite the fact that the majority of the period should be dry. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1240 PM CDT Fri Jul 1 2016 VFR conditions will prevail through the entire 18z TAF period. Diurnal Cu with bases between 3500 and 4500ft will dissipate later this afternoon, followed by mostly clear conditions tonight. Mid/high clouds will gradually increase late tonight into Saturday morning as a frontal boundary over the Ohio River Valley begins to lift back northward. With surface ridge remaining in place across the region, think any showers will hold off until Saturday afternoon/evening. Have instead introduced a mid-level cloud deck at around 10000ft at both KSPI and KDEC after 14z. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Barnes LONG TERM...Bak AVIATION...Barnes
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 214 PM CDT FRI JUL 1 2016 .SHORT TERM... 211 PM CDT Through Saturday... High pressure is centered across the eastern Dakotas and Minnesota this afternoon providing fair conditions along with a modest northerly breeze across much of northern Illinois and northwest Indiana. A little bit of a lake shadow can be seen on visible satellite imagery along with some convergence in the winds stretching from the middle of Lake County, IL south across Cook County. Northeast flow in place on the east side of the boundary has kept temperatures in the low to mid 60s immediately along the lake front with mid 70s in place farther inland. Otherwise, it has been a quiet day across the region with some afternoon fair weather cumulus continuing to erode as dry air advects into the region. Expect skies to go mostly clear this evening and tonight once the cumulus dissipates. The high center is progged to build southeast into northern Illinois by the predawn hours and the ridge axis should settle just to our south during the day Saturday. Favorable conditions for radiational cooling will be in place overnight and leaned towards some of the cooler bias corrected guidance to try to hit the typical cold spots in the CWA which should cool to around the 50 mark and wouldn`t be surprised if a couple spots even dipped into the 40s. Most of the Chicago metro and urban heat island area should hold onto mid even upper 50s though. Expect fair conditions to continue through the day Saturday with light flow allowing a lake breeze to develop. Temperatures should warm into the mid to upper 70s with increasing cirrus streaming overhead. Deubelbeiss && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1241 PM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1241 PM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 18Z TAFs... High pressure will bring fair weather and VFR conditions to the northern Illinois and northwestern Indiana terminals the rest of today and through the day Saturday. The high is currently centered over Minnesota providing a modest northerly breeze to the region, with some easterly component to the winds due to the influence of Lake Michigan for the Chicago Terminals. Winds will gradually trend downward this evening and tonight as the high moves overhead. Winds will likely become light and variable or even calm at some point overnight. Winds should remain light through the morning and early afternoon resulting in low confidence in picking out a prevailing direction, but by early to mid afternoon, a lake breeze should push across the Chicago area terminals turning winds to the east. Deubelbeiss && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 1240 PM CDT FRI JUL 1 2016 .UPDATE... Issued at 1046 AM CDT Fri Jul 1 2016 High pressure will dominate the weather across central Illinois today, providing partly to mostly sunny skies and cool conditions. Current forecast is right on track and requires no updates. && .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1240 PM CDT Fri Jul 1 2016 VFR conditions will prevail through the entire 18z TAF period. Diurnal Cu with bases between 3500 and 4500ft will dissipate later this afternoon, followed by mostly clear conditions tonight. Mid/high clouds will gradually increase late tonight into Saturday morning as a frontal boundary over the Ohio River Valley begins to lift back northward. With surface ridge remaining in place across the region, think any showers will hold off until Saturday afternoon/evening. Have instead introduced a mid-level cloud deck at around 10000ft at both KSPI and KDEC after 14z. && .ILX Watches/Warnings/Advisories... NONE. && $$ UPDATE...Barnes SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Barnes
Area Forecast Discussion National Weather Service Lincoln IL 1240 PM CDT FRI JUL 1 2016 .UPDATE... Issued at 1046 AM CDT Fri Jul 1 2016 High pressure will dominate the weather across central Illinois today, providing partly to mostly sunny skies and cool conditions. Current forecast is right on track and requires no updates. && .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1240 PM CDT Fri Jul 1 2016 VFR conditions will prevail through the entire 18z TAF period. Diurnal Cu with bases between 3500 and 4500ft will dissipate later this afternoon, followed by mostly clear conditions tonight. Mid/high clouds will gradually increase late tonight into Saturday morning as a frontal boundary over the Ohio River Valley begins to lift back northward. With surface ridge remaining in place across the region, think any showers will hold off until Saturday afternoon/evening. Have instead introduced a mid-level cloud deck at around 10000ft at both KSPI and KDEC after 14z. && .ILX Watches/Warnings/Advisories... NONE. && $$ UPDATE...Barnes SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Barnes
Area Forecast Discussion National Weather Service Lincoln IL 1046 AM CDT FRI JUL 1 2016 .UPDATE... Issued at 1046 AM CDT Fri Jul 1 2016 High pressure will dominate the weather across central Illinois today, providing partly to mostly sunny skies and cool conditions. Current forecast is right on track and requires no updates. && .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 610 AM CDT Fri Jul 1 2016 A band of MVFR with local IFR cigs was just north of the forecast area early this morning and was tracking south at about 15 kts. Main question is whether this band of moisture will mix out by mid-morning or will it be able to make it across at least our northern half of the forecast area. Forecast soundings suggest a period of sct-bkn cigs at BMI and PIA with more of a scattered cloud base of 1500-2500 feet further south. Any bkn cigs should lift to VFR as drier air settles south into the forecast area by this afternoon with VFR conditions continuing into the overnight hours. Surface flow will be northerly today at 8 to 15 kts and light northeasterly tonight with speeds of 3 to 7 kts expected. && .ILX Watches/Warnings/Advisories... NONE. && $$ UPDATE...Barnes SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Smith
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 630 AM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 12Z TAFs... 630 am...North/northeast winds will remain in the 10-15kt range through mid afternoon with gusts up to 20kts at times. Higher gusts can be expected near the lake and at gyy. The winds will turn a bit more northeasterly late this afternoon into early this evening as speeds begin to diminish. As high pressure builds across the region tonight...winds will become light and variable and likely calm in many locations. Mvfr cigs will remain sct varying bkn through the morning as they slowly lift to low vfr. Still quite a bit of mvfr cigs across southern WI so opted to maintain prevailing mvfr cigs for this morning. Clouds will eventually scatter out this afternoon into early this evening. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 617 AM CDT FRI JUL 1 2016 .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 610 AM CDT Fri Jul 1 2016 A band of MVFR with local IFR cigs was just north of the forecast area early this morning and was tracking south at about 15 kts. Main question is whether this band of moisture will mix out by mid-morning or will it be able to make it across at least our northern half of the forecast area. Forecast soundings suggest a period of sct-bkn cigs at BMI and PIA with more of a scattered cloud base of 1500-2500 feet further south. Any bkn cigs should lift to VFR as drier air settles south into the forecast area by this afternoon with VFR conditions continuing into the overnight hours. Surface flow will be northely today at 8 to 15 kts and light northeasterly tonight with speeds of 3 to 7 kts expected. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Smith
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 334 AM CDT FRI JUL 1 2016 .SHORT TERM... 333 AM CDT Today through Monday... Main forecast concerns through the Fourth of July Holiday weekend focus on timing and extent of rain/thunderstorm potential Sunday into Monday, primarily south of the I-80 corridor. Scattered thunderstorms were ongoing early this morning across the far southeast corner of the cwa, in advance of a cold front which is pushing southeast across the forecast area. These storms will be out of the area by sunrise as the front completes its transit, and a vigorous mid-level short wave trough moves east of the region. Height rises will develop during the day in the wake of this wave, resulting in surface high pressure building southeast from the upper Mississippi Valley through tonight. Breezy northerly winds will bring cooler/drier air into the region, along with a period of partly-mostly cloudy conditions with an area of extensive stratocu. The long north fetch and winds gusting 20-25 mph over the lake will produce hazardous Lake Michigan swimming conditions at area beaches into this evening. Despite decreasing clouds later this afternoon, highs will likely be limited to the upper 60s along the Lake Michigan shore and into northwest Indiana, while reaching the low-mid 70s farther west across northern Illinois. A cool night can be expected tonight with the surface high in place, and clear to partly cloudy skies allowing strong radiative cooling conditions. Lows may dip to around 50 in typical cool spots like the Fox River valley. Dry weather and moderating temperatures start the weekend Saturday with surface high pressure remaining in place across the area. Some increase in high cloud cover is anticipated, especially across the southern/western portions of the cwa, though temps are expected to warm into the mid-upper 70s in most areas, with a lake breeze cooling shore areas in the afternoon. Guidance is in fairly good agreement in a mid-level short wave trough moving out of the central/southern Rockies late Saturday, and propagating slowly eastward across the mid-Missouri and mid-Mississippi Valley regions through Monday. The low-level baroclinic zone associated with the cold front which moves through the area this morning is expected to become the focus for thunderstorm development across the mid-Missouri Valley by late Saturday night, and from that region into central Illinois and Indiana Sunday into Monday. Forecast models depict a fairly tight northern gradient in qpf fields during the period, with the northern edge of the more significant precip potential remaining generally south of the I-80 corridor. Mid/high cloud cover and low-level east-southeast winds north of the surface low track (through central IL) will help to limit instability across much of the cwa, with the greatest potential for any thunderstorms Sunday into Monday limited to the southern tier or two of cwa counties, with the greatest potential generally on Sunday. With these trends in mind, have decreased/removed pops across northern counties through the period. Ratzer && .LONG TERM... 333 AM CDT Tuesday through Thursday... The slow-moving short wave and surface low which track over central IL/IN Monday are progged to move east of the area Monday night. Flat, broad upper ridging develops in the medium range model guidance through mid-week, though there are indications of a short wave flattening the flow across the region by Wednesday, before ridging strengthens briefly on Thursday. Temperatures should warm through the period and especially Thursday as progged 850 mb temperatures approach +25C. However, the warm front which lifts across the region Wednesday looks to sag back south as a cold front by Thursday evening. The relatively low amplitude of the upper ridge, and the proximity of the surface front during the Wednesday-Thursday period along with associated chances for occasional thunderstorms does lower confidence somewhat in details at this distance, with mid-late next week seeing potentially somewhat active weather. Ratzer && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014 UNTIL 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002 UNTIL MIDNIGHT Saturday. LM...Small Craft Advisory...ILLINOIS NEARSHORE WATERS UNTIL 10 PM Friday. Small Craft Advisory...INDIANA NEARSHORE WATERS UNTIL 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion National Weather Service Lincoln IL 306 AM CDT FRI JUL 1 2016 .SHORT TERM...(Today) ISSUED AT 305 AM CDT Fri Jul 1 2016 Widely scattered showers and thunderstorms continue along and east of a cold front, which at 2 am was located roughly along the I-55 corridor. The front will exit our far east and southeast counties by 14z with winds turning into a northerly direction which will bring in another very pleasant air mass for the next couple of days. The latest surface observations showing some patchy fog and low clouds immediately behind the cold front, but forecast soundings indicate the depth of the moisture to be quite shallow, so what fog and stratus that does develop won`t be around for very long this morning as high pressure to our northwest shifts southeast into the Midwest. Forecast soundings indicate we should be able to mix down from around 875 mb this afternoon which supports afternoon temperatures that will range from the mid to upper 70s north to the middle 80s over far southeast Illinois. && .LONG TERM...(Tonight through Thursday) ISSUED AT 305 AM CDT Fri Jul 1 2016 Main focus remains with the positioning of the heavier rain axis this weekend. The general trend remains with a slightly further south position, which would place the heavy rains generally centered along the I-70 corridor. With an extended period of precipitable waters of around 2 inches, rainfall totals of 3-4 inches appear possible over the southeast CWA and as far north as Mattoon and Jacksonville. Most of this area has been on the dry side the last couple weeks, generally 1/2 inch or less. Given that fact and the more extended period of rain expected, this area should be able to absorb that much rain and thus no flood watches are planned at this time. With a sharp northern boundary continuing to be indicated with the latest models, amounts from about Bloomington northwest continue to trend downward, with totals mostly in the 1/2 to 1 inch range there. In terms of timing, a very substantial dry wedge below 600 mb is shown on the forecast soundings to start Saturday, which will start to moisten up as the day progresses. Have limited most of the mentionable PoP`s to areas from about Havana-Lawrenceville westward, with likely PoP`s over the far southwest CWA near Jacksonville. The NAM is most aggressive in overspreading the rain over the CWA Saturday evening, but the slower GFS/ECMWF solution is preferred with the highest rain chances not arriving until late evening over the northeast CWA. Sunday and Sunday night will feature the highest chances and heaviest amounts, as the southeast CWA will remain wet a good part of Independence Day. However, the remainder of the CWA should see only scattered showers and a few thunderstorms, with mostly dry conditions from I-70 northward by fireworks time. Temperatures will be tricky with the rain this weekend. MOS guidance is generally limiting highs both Saturday and Sunday to the 60s where the rain will be most widespread, and thus have lowered the blended model guidance appropriately, mainly focused over the central third of the forecast area. However, a warming trend will be ongoing through next week as the upper pattern starts to favor a flow out of the Desert Southwest. Highs should start approaching 90 degrees by Wednesday as more typical summertime dew points in the 70s overspread the region. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1152 PM CDT Thu Jun 30 2016 Front is sitting right along I-55 and will continue to move east remainder of the night. Convection has diminished over most of the area except for north and south of the TAF sites. So new TAFs will not have any pcpn mentioned except for maybe VCSH. Once front moves through and pcpn ends, skies will be mainly scattered with SC and mid clouds remainder of the night, though MOS guidance showing some MVFR clouds for the next several hours at all sites, likely SC/stratus from this evenings pcpn, combined with light winds and partly cloudy skies. May need to add a TEMPO group at all sites to account for this. Tomorrow should be mostly sunny with cirrus moving in during the afternoon. Light and variable winds will become northwesterly after FROPA, and then northerly through tomorrow. && .ILX Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Smith LONG TERM...Geelhart AVIATION...Auten
Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 206 AM CDT FRI JUL 1 2016 .UPDATE... 909 PM CDT THE MAIN UPDATES THIS EVENING WAS TO TRIM THUNDER CHANCES TONIGHT. WATER VAPOR Imagery THIS EVENING SHOWS A WELL DEFINED UPPER-LEVEL IMPULSE DIGGING EAST-SOUTHEASTWARD OVER THE UPPER MISSISSIPPI VALLEY. AN ASSOCIATED STRENGTHENING NORTHWESTERLY UPPER-LEVEL JET (~90 KT) IS EXPECTED TO NOSE INTO NORTHERN ILLINOIS LATE THIS EVENING AND INTO THE OVERNIGHT HOURS...WHICH LOOKS TO PLACE THE AREA IN THE FAVORABLE LEFT EXIT REGION OF THIS UPPER JET. BECAUSE OF THIS...IT APPEARS LIKELY THAT SHOWERS WILL CONTINUE TO FESTER OVER THE AREA LATER THIS EVENING THROUGH THE EARLY MORNING HOURS. WHILE AN ISOLATED LIGHTENING STRIKE OR TWO CANT BE RULED OUT...IT APPEARS THE BEST CHANCE OF THIS WOULD BE WEST OF I-39 IN CLOSER PROXIMITY TO INSTABILITY AXIS. SOME OF THE LATEST AMDAR SOUNDINGS OUT OF KMDW INDICATE VERY LITTLE TO NO INSTABILITY OVER NORTHEASTERN ILLINOIS...SO WE HAVE DROPPED THE THUNDER THREAT OVER THIS AREA...GOING WITH JUST SHOWER WORDING. THE SURFACE COLD FRONT WILL GRADUALLY SHIFT OVER THE AREA OVERNIGHT...WITH WINDS BECOMING NORTHERLY BY DAYBREAK. SOME LOWER CLOUDS COULD MOVE OVER THE AREA BY EARLY MORNING IN THE WAKE OF THIS FRONT...BUT THESE CLOUDS WOULD LIKELY GRADUALLY DIMINISH FRIDAY AFTERNOON. KJB && .SHORT TERM... 234 PM CDT Through Friday... Lead impulse with decaying convection looks to perhaps bring some light showers to far southern portions of the CWA rest of this afternoon. Otherwise, attention will be focused to the northwest on the developing convection over IA this afternoon in advance of sharp mid-upper level trough digging into the upper Mississippi Valley. Debris cloudiness over much of the CWA in association with the decaying convection is limiting instability, though some late day clearing could allow for some modest destabilization over our western CWA. Deep layer shear on the order of 30-40kt could be enough to support a marginal severe wind/hail risk despite MLCAPE of less than 1000 j/kg. Better threat of a stronger storm is west of our CWA, where more sfc heating is taking place this afternoon. Even with the weak and weakening instability as the evening wears on, still think the magnitude of the forcing with the strong trough could be enough to allow showers and isolated thunderstorms to march across much of the CWA. Weak pre-frontal trough should shift winds to the northwest behind the convection, but more substantial synoptic cold front will come charging down the lake late after midnight with a wind shift to north. Though expect the lake to get involved, probably leading to an acceleration of the front down the lake with winds near the lake probably veering a bit more northeasterly with a period of gusts of 30+ mph possible late tonight/early Friday near the lake. Some post-frontal stratocumulus appears likely, perhaps enhanced a bit from the lake before land-lake stability flips in the afternoon and skies clear over the lake and behind the expected afternoon lake breeze. Izzi && .LONG TERM... 246 PM CDT Friday night through Thursday... Friday night through Thursday... To start out the period, strong upper level ridging will be in place across the Northern Rockies and Canadian Rockies with northwest flow into the Great Lakes. At the surface, high pressure will be centered directly over northern Illinois and northwest Indiana providing favorable conditions for radiational cooling with clear skies and very light/calm winds. Expect overnight lows to bottom out near 50 in some of the typical low lying cool spots of the CWA while the Chicago Metro area holds onto mid to upper 50s. Quiet weather along with seasonably cool conditions will continue through the day Saturday under the influence of the high. Light flow will allow an afternoon lake breeze to develop. Temperatures inland should top out in the mid to upper 70s while immediately along the lake front we will only see low to mid 70s. Meanwhile, over the weekend, the baroclinic zone is expected to serve as the focus for convection from the Central Plains east across the Mid-Mississippi Valley. Models continue to struggle with the evolution of a wave that is progged to develop along the baroclinic zone Sunday into Monday, though have in general been trending north with the axis of heavy precip over the past couple days. Central and southern Illinois still appear more favored to see strong thunderstorms with the potential for heavy rain Sunday into Sunday night though the NAM for instance still tries to bring convection up through roughly the I-80 corridor. Models are struggling with convective feedback and might be over- deepening the surface low along the boundary as well as the northward push of the baroclinic zone. Convective outflow may actually end up reinforcing the surface boundary south and lack of any significant upper level support would not be conducive of the boundary pushing north. Continue to favor a more southerly solution, but given the model spread and uncertainty, will remain conservative and maintain chance PoPs mainly south of the I-80 corridor. Wherever it does end up setting up, NAM/GFS both suggest PWATs of around two inches will be in place along with the threat for heavy rainfall. The region will undergo a warming trend from Tuesday on as the upper ridge slides east to the mid section of the country and low/mid level southwesterly flow develops across the Midwest. Latest GFS and ECMWF continue to suggest we might see low to mid 20C 850mb temps mid to late next week which would support temperatures hotter than currently advertised by the general model consensus blend we use as a starting point. Given uncertainty in convective chances under an increasingly unstable air mass and some run-to-run inconsistency, opted to not make any changes from the blend, but there remains some concern we may see a heat wave locally by late in the week. The 12Z ECMWF continues to call for low to mid 90s Thursday and Friday, but the 00Z run was cooler. Deubelbeiss && .AVIATION... For the 06Z TAFs... 1225 am...Forecast concerns this period are wind directions/speeds and mvfr cigs. Low pressure over southern Lake Michigan will move east early this morning. A cold front will push across the terminals in the next few hours shifting winds northerly. Winds have turned north/northeast across southeast WI and the front is moving rather slowly down the west side of the lake. Guidance in decent agreement with a wind shift around 09z so maintained current timing but in the 08z-10z time window looks on track. Once winds shift to the north/northeast there will likely be a period of gusts into the high teen/lower 20kts range which will slowly diminish by late morning or early afternoon. Northeast winds will turn more east/northeast later this afternoon and become light and variable this evening as high pressure builds across the region. There is currently quite a bit of bkn/ovc mvfr cigs across southeast WI...which then scatters back across far northern IL. Once winds shift...a period of prevailing mvfr cigs looks reasonable and these will likely persist through at least mid morning but gradually lift by late morning with clouds expected to scatter out this afternoon. Thunderstorms have developed from far southeast Lake Michigan back across eastern IL. All of this convection is expected to remain south and east of the terminals with perhaps a passing shower in the next few hours. But no mention with expected isolated coverage and short duration. cms && .MARINE... 206 am...Low pressure over southwest lower Michigan will move northeast today as high pressure over the northern plains reaches the western lakes region this evening. Between these two features the gradient will become quite strong with northerly winds to 30 kts expected over much of the lake this morning...gradually diminishing from north to south through the day. As the high moves across the lake tonight...winds will turn more westerly. Low pressure is expected to move from the central plains Sunday to the Ohio Valley Monday with weak high pressure across the northern lakes. Easterly winds are expected to develop by Sunday across southern portions of the lake and remain easterly into Tuesday when winds shift more southerly. Depending on the strengthen of this low and the associated gradient...its possible easterly winds Sunday night into Monday may increase into the 10-20kt range over southern Lake Michigan. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014...6 AM Friday TO 6 PM Friday. IN...Beach Hazards Statement...INZ001-INZ002...6 AM Friday TO MIDNIGHT Saturday. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...5 AM Friday TO 10 PM Friday. Small Craft Advisory...LMZ743-LMZ744-LMZ745...5 AM Friday TO 4 AM Saturday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO