259 FXUS65 KTFX 170229 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 829 PM MDT Wed Apr 16 2025 .KEY MESSAGES... - Rain and snow will continue to make their way through the area today, bringing periods of reduced visibility and some areas of slick roads. - Gusty winds could result in some drifting of the snow, particularly along the Rocky Mountain Front and in Southwestern Montana. - After a warm and tranquil end to this week, the cool and unsettled weather pattern returns for next week. && .UPDATE... Updated evening forecast is out. Rain/snow continue to push southward, with the heaviest snowfall shifting over Southwest MT tonight. Snow is ending along the divide/northern Rockies now, thus the current statement ending time for this area looks good. However, snow continues over the Southern Rockies, and a portion of that area might need to be extended overnight, just depending how much the snow decreases in that area over the next few hours. Overall, snow accumulations at lower elevations will be on the light side, generally 1 to 3 inches. Impacts will be limited with melting, but as colder air moves into the CWA overnight, some wet roadways could begin to freeze over by daybreak. Overall, current forecast lows for tonight look on track. Brusda /Issued 454 PM MDT Wed Apr 16 2025/ Updated pops over North Central MT this evening, with a widespread area of moderate snowfall moving northeastward through the CWA. Most snow accumulations are on the grassy areas at lower elevations at this time, but do expect reduced driving visibility, along with some slushy snow accumulations, especially on bridges. Brusda && .DISCUSSION... /Issued 300 PM MDT Wed Apr 16 2025/ - Meteorological Overview: An upper level trough will continue to dig into the Northern Rockies today, bringing a cold front and a round of precipitation to the area. Precipitation will start out as a period of rain at lower elevations before quickly changing over to snowfall within a few hours of precipitation beginning. Snowfall will continue to move southward this evening and overnight tonight as the cold front and trough slide further south, and winds will also pick up across Southwestern Montana as the cold front slows, allowing the pressure gradient to strengthen, with the strongest winds expected in the North South oriented valleys. Snow should generally be on the decrease by sunrise on Thursday as this system gets further south, but a reinforcing upper level disturbance could help kick off a few convective snow showers during the afternoon on Thursday. Upper level ridging will build back into the area for Friday and Saturday, which will bring a period of warmer and more tranquil weather to the area for the end of this week. However, zonal flow will set back up as early as Sunday, which will allow for another period of cooler and unsettled weather that will likely last through next week. - Forecast Confidence & Scenarios: Snowfall accumulations through the next 12-24 hours will largely be dependent on the timing of the changeover to snowfall today and tonight, along with ground temperatures. So far, precipitation has been changing to snow slightly faster than originally forecast, but the strong April sun angle has been keeping accumulations low and generally on elevated/grassy surfaces. Furthermore, pavement temperatures will generally be the biggest factor in impacts with this system, as how quickly the pavement cools off will play a large role in whether or not roadways ice up overnight tonight, along with determining how much accumulates on any paved surfaces. For next week, while confidence is generally high in the overall pattern being on the unsettled side, confidence in any individual system or details that follow from that is quite low at this time. Ludwig && .AVIATION... 17/00Z TAF Period North Central Montana: The main area of light to moderate snow has mostly moved out of this area as of 00Z, allowing conditions to improve to VFR with broken mid- and high-level cloudiness. If winds and clouds continue to decrease, areas of fog will be a concern between 06Z and 16Z, but am not expecting a significant decrease in either. Northerly surface winds should increase again after 16Z. Central Montana: Gusty northerly upslope winds will help maintain mountain-obscuring MVFR/IFR conditions in snow through around 06Z. After then, winds and snow should decrease, but VFR/MVFR ceilings will likely improve to VFR after 12Z. After 16Z, weak instability will allow scattered snow showers to form once again, possibly causing periods of MVFR conditions with a return of gusty northerly winds. Southwest Montana: Gusty northerly winds will gradually decrease at KHLN after 04Z and at KBZN after 06Z before increasing again after 16Z, but they should remain gusty at KEKS through the remainder of the period. A mix of rain and snow with VFR/MVFR conditions will likely become all snow with mountain- obscuring MVFR/IFR conditions by 05Z. This widespread snow should decrease somewhat from north to south between 12Z and 18Z, but similar to Central Montana, weak instability will bring scattered snow showers with periods of MVFR conditions after 18Z. -Coulston Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PRELIMINARY POINT TEMPS/POPS... GTF 29 42 23 50 / 100 30 10 0 CTB 23 39 20 51 / 100 20 0 0 HLN 31 42 24 51 / 80 50 10 0 BZN 27 35 16 43 / 100 90 20 10 WYS 22 33 13 40 / 90 90 40 0 DLN 26 34 19 42 / 90 80 10 0 HVR 26 46 21 53 / 100 10 0 0 LWT 26 36 20 44 / 100 60 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until midnight MDT tonight for East Glacier Park Region-Southern Rocky Mountain Front. Winter Weather Advisory until midnight MDT tonight for Northern High Plains-Southern High Plains. Winter Weather Advisory until 6 AM MDT Thursday for Gates of the Mountains-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Snowy and Judith Mountains-Upper Blackfoot and MacDonald Pass. Winter Weather Advisory until midnight MDT Thursday night for Beaverhead and Western Madison below 6000ft-Canyon Ferry Area- Elkhorn and Boulder Mountains-Gallatin Valley-Helena Valley- Meagher County Valleys-Missouri Headwaters-Northwest Beaverhead County-Ruby Mountains and Southern Beaverhead Mountains. Winter Storm Warning until midnight MDT Thursday night for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Madison River Valley. && $$ http://www.weather.gov/greatfalls