342 FXUS65 KTFX 281736 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1036 AM MST Sat Nov 28 2020 ...AVIATION SECTION UPDATED... .SYNOPSIS... Strong south to west winds will continue through the day today ahead of a southward advancing cold front, which will eventually stall along the Central Montana mountains this evening. Light precipitation is expected over the Continental Divide through much of the day, with light precipitation also being possible along and behind the cold front across Central Montana this afternoon and evening. && .UPDATE... The morning update has been published, with only minor amendments to RH, temperatures and their respective hourly grids. Winds haven't been impressive so far this morning but will keep the High Wind Warning as is since there is still an opportunity for 40 to 70 kt H700 winds to mix to the surface through early this afternoon. The upper level trough axis moves through the region this afternoon as a weak surface cold front advances southwards into North-central MT by this evening. Still looking at most precipitation with this system to be confined to areas along the Divide and in the vicinity of the Little Belt Mountains. RCG && .AVIATION... 1036 AM MST Sat Nov 28 2020 (28/18Z TAF period) Low level wind shear and mountain wave turbulence over Central/North- Central Montana gradually diminish this afternoon. A surface cold front advances south from Canada into North Central Montana through this evening and will likely stall out over the Central Montana mountains tonight. Main impact will be a wind shift from the west to more northerly direction; however, some light rain/snow showers can't be ruled out, especially near the KGTF and KLWT terminals. Otherwise, expect periods of mountain obscuration at times over much of the region for the first half of the TAF period and perhaps the entire period along the Divide. - RCG/Moldan No TAF at KWYS until airport operations resume next spring. Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 140 AM MST Sat Nov 28 2020/ Today through Tuesday...primary forecast concern throughout the period will be winds each and every day, especially today across portions of Central and North Central Montana where a High Wind Warning remains in effect until 22z (3pm Saturday). Fast moving shortwave within zonal flow will slide east across the Northern Rockies and Southern Canada this morning, with the best upper level dynamics generally remaining north of the region and over Southern Alberta. At the surface, low pressure over South Central Alberta early this morning will quickly move east southeast to Southern Manitoba by this afternoon, with a trailing cold front pushing south and across North Central and into Central Montana from late this morning and through the afternoon hours. Ahead of this cold front, a strong pressure gradient will continue to reside in lee of the Rocky Mountain Front and along the Central and Southwest Montana mountains. This strong pressure gradient combined with cross barrier winds of 40-80kts across most of the CWA (strongest winds of 60-80kts will remain over North Central and northern portions of Central Montana) will lead to continued strong and gusty surface winds through the afternoon hours today. At this time the best chance of seeing high wind criteria wind speeds and gusts within the on-going High Wind Warning will be during the morning hours when the pressure gradient and potential for mountain waves (due to favorable upper level thermal profiles) will be the strongest/highest. It should also be noted that isolated near-criteria wind speeds and gusts could occur in some of the north-south orientated valleys of Southwest Montana today, especially over Norris Hill. While precipitation chances are expected to remain over the Rocky Mountain Front through much of the day thanks to upslope conditions from the overall zonal upper level pattern, some light precipitation can not be ruled out in the upslope regions of Central Montana this afternoon/evening along and behind the passing cold front. Winds are expected to decrease quickly this evening as upper level ridging build back in over the Northern Rockies and surface high pressure slides south along the Continental Divide. Lee side surface trough will begin to sharpen once again during the day on Sunday as the next upper level shortwave begins to approach the Pacific Northwest Coast, which will lead to increasing winds in wind prone areas. Winds will continue to remain breezy into the day on Monday as the aforementioned next shortwave approaches the Northern Rockies, with the potential for possibly another high wind event across portions of North Central Montana during the day on Monday. As the shortwave crosses the region Monday night and through the day on Tuesday expect another chance for light precipitation, mainly in the form of snow, especially over the mountains and in northern facing upslope region of Central Montana. - Moldan Tuesday night through next Saturday...overall quite and dry conditions are expected as large scale ridging looks to develop over much of the Western CONUS. It does appear that a period of strong winds could develop once again during the Thursday through Friday timeframe, but confidence in speeds and timing is low at this time. High temperatures through the remainder of the work week and into the start of next week look to be near climatological norms. - Moldan && .PRELIMINARY POINT TEMPS/POPS... GTF 48 24 46 29 / 10 20 0 0 CTB 46 20 42 27 / 0 0 0 0 HLN 44 21 41 18 / 0 0 0 0 BZN 41 13 39 10 / 10 10 0 0 WYS 26 -6 30 -3 / 0 0 0 0 DLN 39 12 36 13 / 10 10 0 0 HVR 43 14 38 24 / 10 0 0 0 LWT 51 20 44 23 / 20 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 3 PM MST this afternoon Blaine... Cascade...Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...Fergus...Hill...Judith Basin...Liberty...Northern Rocky Mountain Front...Southern Rocky Mountain Front...Toole. && $$ http://www.weather.gov/greatfalls