Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/18/22

Area Forecast Discussion
National Weather Service Houston/Galveston TX
633 PM CDT Sun Apr 17 2022 .AVIATION... VFR this evening except in/near SHRA/TSRA that are developing ahead of a cold front. Have MVFR/IFR ceilings developing overnight behind the front with N winds around 5 to 10 knots. Might have to deal with possible fog development for the GLS area. Becoming VFR during the daytime hours tomorrow with slightly stronger (maybe gusty) N to NE winds. E winds 5 to 10 knots tomorrow evening and VFR. 42 && .CLIMATE... Galveston has a low temperature so far today of 75 degrees. If this holds through the end of the day, this will tie the record high minimum temperature record for April 17th of 75 degrees set in 1967 and 1908. 42 && .PREV DISCUSSION... /ISSUED 348 PM CDT Sun Apr 17 2022/ SHORT TERM [Through Monday Night]... Front will be making its way across the region this evening and off the coast after midnight. Aircraft soundings out of the Houston area still showing a pretty decent cap in place. That said, there is still plenty of sun in place and time for additional heating, so any localized breaks in the cap would allow for a thunderstorm or two develop and mix in with iso-sct shras along the boundary as a few of the CAMs are suggesting. Looking like we might see some lingering morning low cloudiness on Monday, but that should erode during the mid morning hours and leave msunny skies, drier and less humid conditions. Clear & cool Monday night. (Enjoy it...considering it might be the only night of the week most of us see below average temps). 47 LONG TERM [Tuesday Through Sunday]... A period of unseasonably warm weather with increasing humidity will characterize the remainder of the upcoming week. By Tuesday, the eastward departure of surface high pressure over the Central Plains will allow for onshore winds to quickly redevelop, while a developing lee cyclone in Western CO will tighten the synoptic pressure gradient across the region. As a result, both temperatures and dewpoints will be on an upward trend on Tuesday with afternoon highs inching back towards the 80s. As increasing cloud cover and WAA remain the story overnight, lows will settle mostly into the mid/upper 60s at most locations. While flow aloft remains mostly zonal on Wednesday, a very weak midlevel shortwave will pass just to our north. As total PW values climb above 1.5 in during this time, a few scattered to isolated showers and questions are not out of the question. That being said, coverage should be limited should storms materialize and as such have maintained low PoP values in the forecast for the time being. Precipitation chances otherwise remain near zero for the remainder of the week while a relatively tight pressure gradient will allow for the warming trend to continue into the weekend. Most locations should see highs in the low/mid 80s by Wednesday and the mid/upper 80s on Thursday. By Friday, locations in the northern zones may flirt with 90 degrees. Overnight lows during this time will also remain elevated, likely near but just below record high minimum values with most locations in the upper 60s to low 70s. Heading into the weekend, an amplified upper trough looks to move into the Northern/Central Plains while a cold front extending from its associated surface low will move through the South Central CONUS. Model timing of this feature remains in poor agreement, with the latest GFS showing the front at our doorstep by early Sunday while the ECMWF indicates a slower progression with the boundary arriving on Monday. Showers/storms associated with this feature will bring us our next chance of rainfall. Cady MARINE... Light onshore winds remain in store this evening ahead of an approaching surface cold frontal boundary overnight. Moderate offshore winds will develop behind the departing front, though winds will quickly turn to the east and later southeast by early Tuesday. Moderate onshore winds will persist through the remainder of the week, resulting in elevated seas. This will likely require caution flags and/or advisories during this time. Additionally, these conditions will be favorable for the development of strong rip currents along Gulf-facing beaches. Cady && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 59 80 54 81 66 / 10 0 0 0 20 Houston (IAH) 65 82 58 79 68 / 30 0 0 0 10 Galveston (GLS) 70 80 66 76 71 / 30 0 0 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
900 PM CDT Sun Apr 17 2022 .UPDATE... Issued at 859 PM CDT Sun Apr 17 2022 The going forecast message continues on track, and that is snow late this evening into overnight tapering to light snow/drizzle during the Monday morning commute. While some light slush may occur on some bridges along with some snow on grass in places, this is still looking very likely to not be of notable impact. Will have to watch some surface air temperatures dipping to around freezing in the early morning when some drizzle, but that too doesn`t look to be a big deal given pavement temperatures lagging air temperatures by an appreciable amount at present. The primary upper level short wave trough for tonight`s snow is draped from central/eastern Iowa into eastern Missouri, with a couple of embedded waves comprising this. One of these was fairly evident on regional radar imagery in far western Illinois moving east-northeast. An enhanced area of lift and associated precipitation has been persistent ahead of this and is into the far western CWA as of 845 PM. The leading edge of this has slowed some due to the presence of dry air below 750 mb as noted on the 00Z DVN and ILX soundings and area aircraft soundings. There is limited moisture transport and isentropic ascent ahead of this wave, due to its quick progression and a lot of convection upstream in the LLJ flow. This embedded wave is also outrunning the coldest thermal profiles, and what was earlier several observation sites below 1SM in southern Iowa and northern Missouri is now a site or two very briefly doing that in western Illinois. The precipitation is actually onsetting as rain on its leading edge with boundary layer temperatures in the western CWA still in the low 40s. Overall this means the west-to-east width of the snow area has diminished from earlier on the Iowa/Missouri border. So while heavier rates are still anticipated to occur in parts of the CWA, it should be quite temporary. The locations that seem a smidge favored to have a possible longer duration of snow based on radar trends and high-resolution model solutions are LaSalle, Lee, Ogle, and DeKalb Counties. In the Chicago metro, snow still looks to onset around midnight with most of the snow ending by 4-5 A.M. Some CAMs try to hint at maybe some lake enhancement with the low- level flow off the lake, but that seems like a markedly low contribution if it were to occur. With the aforementioned short wave trough`s passage across the CWA late tonight into the pre- dawn hours, the loss of ice nuclei still favors a transition to light snow/drizzle ("snizzle"). Pavements temperatures at some sites in the coldest part of the CWA (far northern/northwestern Chicago suburbs) are in the mid 40s as of 845 PM. While these will drop as rain moves in and changes to snow, it shows it is a ways from freezing. So unless under a temporary mesoscale enhanced area of snow, the ability to get accumulation on the roads remains quite limited. Also, while some air temperatures are touching 32 along the Illinois/Wisconsin border due in part to thin clouds early this evening, the lagging pavement should help to prevent much for slick spots on main roads (apart from maybe some overpasses) during the early morning as drizzle/mist may be favored. MTF && .SHORT TERM... Issued at 252 PM CDT Sun Apr 17 2022 Through Monday night... Sharp trough will move across the area tonight and bring yet another bout of April snow to much of the area, though not expecting much accumulation and what does accumulate should be mostly confined to grassy and elevated surfaces. Extensive north- south band of precipitation already evident on regional radar mosaic extending from MN south to the Ozarks. It is this band that will continue east in association with the trough, though the precipitation will encounter very dry low levels initially that will need to be saturated via top down saturation. The dry low levels will also result in evaporative cooling which should result in much of the area seeing primarily snow tonight, though some rain could mix in south of the IL and Kankakee Rivers. Once the column saturates and snow begins, it appears as though there could be a few hours of snow, which could fall at a pretty respectable rate at times. Surface temps are expected to be near or just above freezing and when combined with initially above freezing ground and pavement temps, shouldn`t favor accumulation. However, forecast soundings do show very steep lapse rates aloft and strong ascent in the left exit region of approaching upper level jet, there is concern that snow could fall rather heavily at times with some embedded convective elements. Any heavier bursts of snow will probably knock sfc temps down to around freezing and lead to some accumulations, perhaps locally an inch of slushy accumulation. Can`t totally rule out some slushy accums on bridges and overpasses, but with such marginal temps this appears pretty unlikely. As the trough axis passes east of the area late tonight, substantial drying will take place in mid and upper levels. Forecast soundings show a deep low level saturated layer remaining with absence of mid-level moisture leaving the stratus deck void of ice nuclei necessary for snow. Weak ascent within this stratus deck will likely result in drizzle or snizzle (drizzle snow grain mix) for a few hours tomorrow morning. Sfc cold front will move across the area later Monday morning, resulting in wind shift to westerly, which should lead to thinning/breaking up of stratus and end of drizzle threat. Cold air advection Monday afternoon, particularly aloft, will result in steepening low level lapse rates and deepening boundary layer. With vort max associated with the heart of the upper trough pivoting toward the area during the afternoon, will probably see some scattered snow/graupel showers develop. Coverage looks to be greatest eastern CWA into northwest Indiana with surface temps too warm for accumulation, but still unseasonably cold for April. The steepening lapse rates and cold advection will also allow for strong and gusty west-northwest winds Monday afternoon and evening. Gusts over 30 mph are likely with gusts as high as 40 mph possible, particular in any snow showers late in the afternoon/early in the evening. - Izzi && .LONG TERM... Issued at 250 PM CDT Sun Apr 17 2022 Tuesday through Sunday... Tuesday starts under northwesterly flow and cold-air advection (CAA) in the wake of Monday`s low pressure system, with a surface ridge to our west. Low temperatures will be at or below freezing Tuesday morning except near Lake Michigan, where the moderating water temperature will keep temperatures in the mid 30s. Warmer weather is in store as the ridge axis shifts overhead Tuesday afternoon. This ridge passage will weaken overall synoptic wind flow, which in turn will allow a lake breeze to set up in the late morning/early afternoon, switching winds to the northeast near the lake. 925 mb temperatures will jump above freezing as the ridge axis passes overhead , which when combined with mostly clear to partly cloudy skies will allow high temperatures to climb to around 50 degrees, although the lake breeze will keep near-lake temperatures in the mid 40s. Winds will become southerly Tuesday night as the ridge axis moves east, in addition to the approach of our next front. Warm-air advection (WAA) will set up in this southerly flow, leading to lows near 40, and highs in the 50s on Wednesday. Precipitation starts early Wednesday morning as a warm front moves through. With a boundary nearby, WAA and ample moisture, there is a decent chance for some isolated thunderstorms to develop Wednesday afternoon. Additionally a 50+ kt low-level jet (LLJ) will accompany the warm front, potentially bringing surface wind gusts of 35 to 40 mph in the afternoon. The cold front associated with this system will be relatively weak, and doesn`t pass through until overnight Wednesday/early Thursday morning, with decent WAA occurring the entire time. Temperatures will be even warmer on Thursday, as we may quickly jump from sub-seasonal temperatures to above normal temperatures, with lows in the mid to upper 40s, and highs in the upper 60s to near 70! Models are indicating that another weather systems moves in quickly behind the Wednesday system, with a warm front moving up from the south Thursday afternoon. Disagreement on the timing and location of this system continues, so confidence in exactly when precipitation occurs next weekend is low. But presently models agree that under continued southerly flow and WAA, temperatures will be above normal Friday and Saturday, with lows in the 50s and near 60, and highs in the 70s, and approaching 80 on Saturday. Under this warm, moist scenario there will be a chance for showers and possible afternoon thunderstorms throughout next weekend. BKL && .AVIATION... For the 00Z TAFs... Several aviation concerns through the TAF period: 1. Band of rain (likely switching to all snow) reaching the terminals around midnight (5Z) 2. Confidence is high in IFR vis/cigs prevailing through the overnight hours with periods of LIFR likely, possibly as early as snow onset (VLIFR not out of the question based on upstream trends) 3. Snow switches over to drizzle/tiny ice needles early Monday morning with continued IFR cigs with lingering LIFR vis/cigs possible (10-14Z) 4. Scattered rain/snow/graupel showers are possible in the afternoon - may mix down higher gusts to near 40 kt Quiet conditions are expected through the evening hours ahead of our approaching weather system with light easterly winds. A lead arc of precipitation is currently along an axis from Moline to Peoria to Bloomington. This will continue to lift northeast toward the area. Have this timed out to reach the terminals around 5Z. At this time it is falling mainly as rain, with a transition to snow beginning on the northwest side. Further to the northwest across east central IA, snow also continues with LIFR to occasionally VLIFR vis occurring where snowfall rates are highest. Expect this lead arc of rain to transition over to snow on its approach, thus will maintain starting the TAF off as snow, although a brief tempo of -RASN may be considered prior to that. Did move up the PROB30 3/4SM vis to 6-9Z to account for the expectation for quickly deteriorating conditions after precipitation onset. It is not out of the question that we may see vis briefly dip to VLIFR as has been seen upstream, but confidence is too low to have a formal mention in the TAF. Once the lead band of snow moves through a loss of cloud ice toward daybreak should help reduce snowfall rates with drizzle/small ice needles persisting through mid morning along with some fog development. Gridded model guidance has been somewhat aggressive with lowering vis during this period for the Chicago area terminals so opted to introduce a PROB30 for LIFR vis possible from 10-14Z. Expect improving vis and cigs through the daylight hours tomorrow with lingering light rain/snow showers. Winds also become gusty out of the WNW in the afternoon with gusts to near 30kt possible into the evening. There remains a signal for scattered rain/snow/graupel showers in the afternoon as well which could mix down even higher gusts to near 40 kt beneath any showers that develop. Petr && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...LMZ744-LMZ745...1 PM Monday to 3 PM Tuesday. Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743...1 PM Monday to 10 AM Tuesday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at: