FXUS65 KTFX 050309 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 810 PM MST Mon Mar 4 2024 Updated forecast section .SYNOPSIS... After tapering off this evening, snowfall returns to Southwestern Montana on Tuesday as a fast moving weather system moves across the Snake River Valley. Further north, expect temperatures to moderate a bit with most areas seeing temperatures in the mid 30s. Beyond tomorrow, expect temperatures to warm up across the area through the end of the week. && .UPDATE... 8 PM Update...Adjusted overnight lows towards current trends, with w ind chill values around 15 below for areas north of Highway 2 overnight. Otherwise, light snow showers moving from west to east across the CWA are starting to diminish a bit. That trend should continue for most areas, expect the Rocky Mountain Front where they will continue overnight. A band of snow moving through the West Yellowstone area currently, should also diminish in a bit, with a break in the snow in this area until the next system arrives on Tuesday morning. Blowing snow could also be an impact on Tue, especially for areas south of I-90 from Butte to Bozeman. Brusda 6 PM Update...Forecast updated for this evening. Heavy snow is falling in the West Yellowstone area, so the start time for the winter weather advisory has begun for that area, with snow accumulations up to 5 inches expected tonight. Overnight lows were adjusted a bit colder over North Central MT, as daytime highs today did not get as warm as forecasted. Brusda && .AVIATION... 553 PM MST Mon Mar 4 2024 (05/00Z TAF Period) Note: The NWS Great Falls Weather Forecast Office manages the following TAFs: KCTB, KHVR, KGTF, KLWT, KHLN, KBZN and KEKS. North Central Montana: Ceilings lower, this evening and continuing into tomorrow, while areas of mist develop. Conditions are forecast to fall into the MVFR range at our north central Montana airfields during the overnight hours and into tomorrow. Gusty winds to 35KT are forecast, along the Northern Rocky Mountain Front, while generally light and shifting winds prevail across the remainder of this area. Central Montana: VFR conditions prevail for the duration of this 05/00Z TAF period. Winds shift between a northeasterly to southwesterly direction, with gusts to as high as 26KT across portions of central Montana. After 05/18Z, winds, generally, become light and variable. Southwest Montana: Conditions degrade throughout this forecast period, falling into the LIFR range, in snow and blowing snow or mist/fog, at times. Gusty winds up to between 35KT and 45KT are forecast across the mountains of southern southwest Montana and through the mountain valleys/passes for much of this TAF forecast period. In General: Lowering ceilings favor increasingly obscured mountains. - Fogleman Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 553 PM MST Mon Mar 4 2024/ Key points: -Snow showers continue across Southwestern Montana today and Tuesday -Warmer and drier weather is expected for the second half of the week Short Term (through Tuesday)... Scattered snow showers are expected across Southwestern Montana as the warm March sunshine destabilizes a cold air mass across the area. We will have to watch these this afternoon for a few heavier snow showers that could put down a quick half inch or so and cause brief reductions in visibility to under a mile at times, but the overall disorganized nature of these snow showers should help to keep impacts isolated. As we head into the day on Tuesday, a low pressure system moving along a stationary front will push through Southwestern Montana, bringing a round of mostly light to moderate snowfall across areas along and near the Montana-Idaho border. With that said, there could be an area along the stationary front that sees enhanced snowfall, with periods of heavy snow with under a half mile visibility and snowfall rates in excess of 1 inch/hour. At this time, it appears that the greatest risk for this type of snowfall is south of a line from Bozeman to Dillon. While I am holding off on any sort of upgrade to a Winter Storm Warning at this time, should this band set up some areas could see in excess of a foot of snowfall thanks to the orographic and frontogenetic (mountain- induced and front-induced, respectively), forces at play. Snowfall amounts were nudged upwards to account for this possibility. Extended (Wednesday through next Monday)... On the heels of this system, expect clearing skies across the area as surface winds turn westerly/southwesterly thanks to building upper level ridging. With this ridge in place through the end of the week, expect temperatures to moderate to near to near to above average temperatures across the area with breezy, but otherwise tranquil, conditions across the area. Our upper level ridge will begin to break down as we head into next week, which will allow for a more active pattern to set up for the beginning of next week. Ludwig && .PRELIMINARY POINT TEMPS/POPS... GTF 7 36 14 37 / 10 0 0 0 CTB -3 29 6 31 / 0 0 0 0 HLN 12 33 14 35 / 20 20 10 0 BZN 7 29 13 33 / 40 40 40 10 WYS 1 27 9 29 / 90 90 80 50 DLN 5 30 14 32 / 20 40 30 10 HVR -2 21 6 23 / 10 0 10 10 LWT 11 32 12 32 / 30 10 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 5 AM MST Wednesday for Gallatin and Madison County Mountains and Centennial Mountains. Winter Weather Advisory from 5 AM Tuesday to 5 AM MST Wednesday for Madison River Valley-Ruby Mountains and Southern Beaverhead Mountains. && $$ http://www.weather.gov/greatfalls