Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/10/16


Area Forecast Discussion
National Weather Service San Diego CA
827 AM PDT MON OCT 10 2016 .SYNOPSIS... Increasing onshore flow and a slowly deepening marine layer will bring cooling and a return of night and morning low clouds and fog west of the mountains this week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Skies were clear across the entire CWA except for some patchy high clouds. The 12Z Miramar sounding had a sfc-based inversion with a maximum temperature of 23.4 degrees C at 2600 FT. This was about 2 degrees C lower than yesterday. The surface pressure gradients were weakening offshore from NV, but holding weak onshore to the lower deserts. Winds were light. No changes to the current forecast. Only forecast issue may be fog late tonight into Tue morning as the marine air returns. From previous discussion... .SHORT TERM (Today through Wednesday)... Through Wednesday...a weak trough of low pressure off the California coast will move slowly eastward and inland into California. This will bring stronger onshore flow with a cooling trend...deepening of the marine layer...and stronger and gusty southwest to west winds in the mountains and deserts. High temperatures will cool from 5 to 10 degrees above average today...to near average on Tuesday...and a few degrees below average on Wednesday. Aircraft soundings show a shallow marine inversion...with the marine layer around 500 feet deep and surface reports show a recovery in dewpoints near the coast...generally 10 to 15 degrees higher than 24hours ago...into the mid 50s to lower 60s. Satellite imagery shows extensive stratus beyond the islands offshore of Southern California...and along the central California coast spreading southward and into the westward Santa Barbara Channel. There is also stratus near the Baja coast...but still well south of Tijuana and not spreading northward. Some patchy stratus could develop near the coasts of San Diego and possibly Orange County through sunrise with some patchy dense fog possible. More widespread stratus is expected the following two nights with low clouds spreading into the western valleys for Tuesday morning...and into portions of the inland valleys for Wednesday morning. && .LONG TERM (Thursday through Sunday)... For Thursday...weak high pressure aloft near Southern California will bring slight warming with high temperatures near to slightly above average. For Friday through next weekend...a mid-latitude trough of low pressure over the eastern Pacific will gradually progress inland into the western states with a spread in timing and strength among the global models with individual shortwaves within this pattern. For Southern California...this will bring slow cooling with a marine layer deep enough for night and morning coastal low clouds and patchy fog to spread into portions of the inland valleys. For early next week...there is the potential for one of these shortwaves to bring a chance of precipitation to Southern California. && .AVIATION... 101500Z...FEW-BKN cirrus AOA 15,000 ft MSL and unrestricted visibility will prevail over most of the region through 00Z Wednesday. The exception will be the coast and western valleys, where patchy low clouds or fog may return after 04Z and slowly increase in coverage through 12Z. Initially bases should be between 500 and 900 ft MSL, but they may lower overnight. Reduced visibility of 1 sm or less appears likely along the coastal mesas between 10Z and 16Z, with impacts probable for KCRQ. KSAN and KSNA should remain above 3 sm most of the night, though FG or VCFG could creep in between 10z and 16z. Conditions will improve after 16Z Tuesday. && .MARINE... No hazardous marine weather is expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX Watches/Warnings/Advisories... CA...None. PZ...None. && $$ PUBLIC...JAD/17 AVIATION/MARINE...Albright
Area Forecast Discussion
National Weather Service Great Falls MT
915 AM MDT Mon Oct 10 2016 .UPDATE... Snowfall...with isolated areas of freezing rain or sleet...has spread across northern portions of the forecast area as expected this morning. Winter storm warnings and advisories remain in effect as posted. MT DOT road reports indicate snow and ice covered conditions generally north of a line from Bynum to Fort Benton to Havre, and with higher impacts due to blowing and drifting snow across much of Glacier County. Where freezing rain has occurred, reports suggest only glazing on cars or handrails, but with wet road surfaces. Radar is showing three distinct bands of precipitation across the area, so expect periods of snow to continue through this afternoon with a few breaks in between bands. Water vapor satellite imagery shows the shortwave trough axis now over northwest MT, and is followed by a core of dry air aloft. Therefore, expect precipitation to taper starting later this morning over our northwest zones, and continuing to end from west to east through the afternoon. Overall forecast remains in good shape, so have not made any changes with this update. PN && .AVIATION... Updated 1145Z. Very moist, slow-moving trough over southwest Canada and Northern Rockies will keep -RA/-RASN/-SN with MVFR to LIFR ceilings over much of central MT today. Isolated pockets of -FZRA/ice pellets are also possible this morning vcnty KGTF, mainly impacting aircraft surfaces as ground temps are warm enough to keep runway damp. Areas of -RA/ -RASN will transition to -SN as colder air moves south through the day, with MVFR/IFR conditions expected at KHLN/KEKS/KBZN this evening. Precip-induced BR/FG will also impact KCTB/KHVR/KGTF/KLWT this morning. Waranauskas && .PREV DISCUSSION... /ISSUED 545 AM MDT Mon Oct 10 2016/ Today through Wednesday Evening...Current winter storm warnings and advisories remain in effect with no changes at this time. Forecast is on track for widespread, mostly light snow for central and north central MT today as slow-moving shortwave trof makes its way across southwest Canada and the Northern Rockies. Snow has been falling overnight along and north of line from near Augusta to Havre/Chinook, with light rain/drizzle and rain/snow mix over Cascade and southern Chouteau counties. As a colder Canadian airmass spreads further south through the day, light rain will transition to light snow around Great Falls/Helena/ Lewistown and continue into the evening hours. Meanwhile, southwest MT remains mostly dry through early aftn, with valley rain/mtn snow developing later in the day, then light snow tonight. Though forecast model solutions have varied little for past several runs, there is still some differences on the evolution of the moisture accompanying the shortwave. Of note, the NAM model sweeps out the initial moisture plume over the region this morning more aggressively than the GFS or ECMWF models. But given the somewhat slow eastward movement of the trof axis and additional moisture evident upstream in Idaho, current forecast leans more toward the GFS/EC solutions. That will keep the light snow going a few hours longer, but eventually it does taper off tonight/early Tues morning for the Hiline and central counties, while lingering into early Tues aftn over southwest MT. Clearing skies begin in earnest Tues aftn as the trof axis swings through the state and all snow should be over by 6pm Tues. What snow does accumulate won`t last long as dry conditions under a building high pressure ridge are on the way for Wed, with temperatures warming back into the upper 30s to upper 40s Wed aftn. Waranauskas Wednesday night through Monday...A rather progressive westerly flow aloft will reside over the region during the extended period. As a result, no significant storms are expected for areas east of the divide, but do expect some scattered showers, windy conditions at times and fluctuating temperatures in-between systems. Generally, we will be mostly dry through Thursday, then the first upper level disturbance moves through Thursday night/Friday. Most of the precipitation will be confined to the western mountains and Southwest MT with this system. Winds will increase behind this system, especially for Saturday over the Rocky Mountain Front. At this time, wind speeds should remain below warning criteria. Expect passing showers across the region from Saturday night through Monday, with the Rocky Mountain Front the most likely area to receive precipitation. Afternoon temperatures will slowly moderate back towards seasonal normals from Friday through Monday. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF 34 23 32 22 / 70 30 20 0 CTB 30 20 29 16 / 100 30 10 0 HLN 51 29 40 27 / 40 40 20 0 BZN 63 32 40 26 / 30 50 40 0 WEY 57 35 44 24 / 20 50 50 10 DLN 64 32 42 26 / 20 30 30 0 HVR 34 24 31 17 / 100 40 10 0 LWT 49 23 32 21 / 30 50 40 10 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight MDT tonight Eastern Pondera...Eastern Teton...Liberty...Toole. Winter Weather Advisory until midnight MDT tonight below 5000 feet for Southern Rocky Mountain Front. Winter Storm Warning until midnight MDT tonight above 5000 feet for Southern Rocky Mountain Front. Winter Weather Advisory until 6 PM MDT this evening Blaine... Hill. Winter Storm Warning until midnight MDT tonight Eastern Glacier...Northern Rocky Mountain Front. && $$ weather.gov/greatfalls
Area Forecast Discussion
National Weather Service Great Falls MT
257 PM MDT Mon Oct 10 2016 .DISCUSSION... Tonight through Wednesday...Snow showers continue over the Northern Rockies this afternoon as the upper level trough axis lifts across southeast Alberta. These showers may produce up to an additional half inch of snow at lower elevations, and up to two more inches new snow at higher elevations. Web cams show mostly snow covered roads so will continue the winter weather headlines into this evening. Further east, snowfall has ended in Hill and Blaine counties, so have cancelled the winter weather advisory there with no new accumulation expected. Areas where wet roads persist will be subject to icing tonight as temperatures drop well into the 20s for most areas. The passing upper level trough is tightening the height gradient across the southwest, resulting in stronger west-southwest winds aloft. Water vapor imagery shows moisture organizing over southeast ID, poised to move back in to SW MT tonight. In short, while conditions gradually improve tonight in the north, expect increasing chances for snow over southwest MT tonight into early Tuesday. Short-term model guidance suggest 2-4 inches accumulation in this area. Snow impacts should be mainly over mountain areas so have no posted an winter weather advisory. However, will need to monitor this area for a low- confidence but potential snow band that could produce a period of moderate to heavy snow across southwest MT including Bozeman early Tuesday morning. A strong surface high pressure settles in by Tuesday evening, gradually push all precipitation away into eastern MT. Ridging aloft ensues on Wednesday allowing for clear skies and a cold morning. Temperatures finally begin to rebound on Wednesday. PN Wednesday night through Monday...A rather progressive westerly flow aloft will reside over the region during the extended period. As a result, no significant storms are expected for areas east of the divide, but do expect some scattered showers, windy conditions at times and fluctuating temperatures in-between systems. Generally, we will be mostly dry through Thursday, then the first upper level disturbance moves through Thursday night/Friday. Most of the precipitation will be confined to the western mountains and Southwest MT with this system. Winds will increase behind this system, especially for Saturday over the Rocky Mountain Front. At this time, wind speeds should remain below warning criteria. Expect passing showers across the region from Saturday night through Monday, with the Rocky Mountain Front the most likely area to receive precipitation. Afternoon temperatures will slowly moderate back towards seasonal normals from Friday through Monday. Brusda && .AVIATION... Updated 1145Z. Very moist, slow-moving trough over southwest Canada and Northern Rockies will keep -RA/-RASN/-SN with MVFR to LIFR ceilings over much of central MT today. Isolated pockets of -FZRA/ice pellets are also possible this morning vcnty KGTF, mainly impacting aircraft surfaces as ground temps are warm enough to keep runway damp. Areas of -RA/ -RASN will transition to -SN as colder air moves south through the day, with MVFR/IFR conditions expected at KHLN/KEKS/KBZN this evening. Precip-induced BR/FG will also impact KCTB/KHVR/KGTF/KLWT this morning. Waranauskas && .PRELIMINARY POINT TEMPS/POPS... GTF 24 34 21 48 / 30 30 0 0 CTB 18 30 12 37 / 40 30 0 0 HLN 28 40 27 53 / 40 30 0 0 BZN 33 40 26 50 / 80 80 0 0 WEY 39 44 24 47 / 60 60 10 0 DLN 34 42 26 51 / 50 50 0 0 HVR 23 32 17 36 / 20 20 0 0 LWT 26 32 20 47 / 60 60 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight MDT tonight Eastern Pondera...Eastern Teton...Liberty...Toole. Winter Weather Advisory until midnight MDT tonight below 5000 feet for Southern Rocky Mountain Front. Winter Storm Warning until midnight MDT tonight above 5000 feet for Southern Rocky Mountain Front. Winter Storm Warning until midnight MDT tonight Eastern Glacier...Northern Rocky Mountain Front. && $$ weather.gov/greatfalls