FXUS65 KTFX 142327 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 427 PM MST Fri Feb 14 2025 Aviation Section Updated. .KEY MESSAGES... - Largely minor impacts from snow through Saturday morning. - Another period of snow Sunday into much of early next week. - Cold through much of the next week, coldest Tuesday and Wednesday mornings. - Confidence increasing in a trend toward milder and breezier conditions late next week. && .DISCUSSION... /Issued 147 PM MST Fri Feb 14 2025/ - Meteorological Overview: Broad upper troughing extending from the Pacific Northwest all the way to the Desert Southwest will result in a period of snow continuing across the Northern Rockies through tonight into early Saturday. Although the most favorable forcing from the upper level trough will miss the region to the south, embedded features within the troughing across the Northern Rockies will combine with slight orographic forcing to locally enhance snowfall amounts. Overall, this initial snow event will pose minor impacts for most, with the greatest chance for more impactful snow in the Gallatin Valley, where a northwesterly flow just off the surface may locally enhance snowfall amounts in Bozeman. Snow from this event tapers Saturday, but may not end before the next wave of snow begins to move in late Saturday night. Although brief upper level ridging moves in across the Pacific Northwest late Saturday into Sunday, an upper level trough will quickly break down the ridge during the day Sunday. Additionally, a rather potent closed upper low across Manitoba will drop southward closer to the border Sunday into Monday with a lagging, somewhat inverted, trough sagging southward from AB/SK toward the Northern Rockies Monday into Tuesday. These factors will all combine to result in a longer duration snow across the region, with impacts looking to be most focused across Central Montana at this time. Ensembles are converging on a strong surface high sagging south from AB/SK for Tuesday morning through Wednesday morning, which would result in very cold mornings across the plains. After that, ensemble averages point toward a milder period with breezy winds within a more zonal flow aloft. Deterministic guidance still features potent embedded waves traversing through this flow however, which would keep the door open to at least low-end chances for precipitation late next week. -AM - Forecast Confidence & Scenarios: Snow Through Saturday: The greatest uncertainty continues to be in the southern end of the Gallatin Valley for this event, including the city of Bozeman. Probabilistic guidance gives a less than 10% for 6 inches of snow there, but pattern recognition suggests snowfall totals around that much seems like a reasonable outcome. Otherwise minor snow is forecast across the rest of the region. Long Duration Snow Sunday into Early Next Week: The mountains of Central Montana and the Rocky Mountain Front have a greater than 50% chance for total snow in excess of a foot over 72 hours ending Tuesday afternoon. At lower elevations north of I-90 and south of a Browning to Conrad to Great Falls to Lewistown line there is a greater than 50% chance for 6 inches of snow over the same timeframe. Snow over this timeframe will fluctuate from north to south, which bring about uncertainty with respect to exact timing for greater impacts at this time. A Winter Storm Watch was issued where confidence was highest for the potential for moderate impacts. Coldest Temperatures Tuesday and Wednesday Morning: Probabilistic guidance gives a greater than 60% chance for lows of -20F or less across the Hi-Line Tuesday and Wednesday morning, with the chance for -30F lows greater than 50% in northern Hill and Blaine counties over the same timeframe. Milder and Breezier Late Next Week: Probabilistic guidance gives anywhere between a 40 and 60% chance for highs of 40F or greater across the plains west of I-15 next Friday. The chance for a gust in excess of 40 mph on Friday is greater than 50% for the same area, and exceeds 80% close to the Rocky Mountain Front. -AM && .AVIATION... 15/00Z TAF Period Areas of primarily light snow will maintain IFR/MVFR conditions across most terminals this evening, though cannot rule out some brief LIFR in moderate snow at KLWT and KBZN. Some improvement is likely late tonight as precipitation diminishes, but areas of low clouds are likely to persist with potentially some patchy fog development as well in areas that do see lesser clouds late tonight into Saturday morning. More widespread improvement is likely by Saturday afternoon but areas of lower to mid level clouds will maintain some mountain obscuration. Hoenisch Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .HYDROLOGY... The flood advisory continues for the Madison River in Ennis because of an ice jam. Over the past few days, emergency manager in Ennis reported the ice jam is not getting better, with flooding continuing in Ennis Lions Club Park. The minor flooding is continues to affect areas eastward towards Odell Creek, along with southward towards Highway 287. There is some potential that the ice jam could result in water going over Highway 287 if the ice jam continues to grow. Thus the flood advisory will continue until the ice jam breaks and the water recedes. Brusda && .PRELIMINARY POINT TEMPS/POPS... GTF -3 5 -5 6 / 80 30 30 70 CTB -12 1 -11 4 / 60 30 0 40 HLN -2 19 4 15 / 60 30 20 80 BZN 1 18 3 21 / 90 50 20 80 WYS 11 24 5 24 / 80 40 40 100 DLN 10 27 12 30 / 60 20 0 40 HVR -10 -2 -19 0 / 90 30 0 10 LWT -6 3 -6 7 / 80 30 40 60 && .TFX WATCHES/WARNINGS/ADVISORIES... Cold Weather Advisory until noon MST Saturday for Eastern Glacier, Western Toole, and Central Pondera-Eastern Toole and Liberty. Winter Storm Watch from Sunday morning through Monday afternoon for Big Belt, Bridger and Castle Mountains-Cascade County below 5000ft-East Glacier Park Region-Eastern Pondera and Eastern Teton-Gates of the Mountains-Judith Basin County and Judith Gap- Little Belt and Highwood Mountains-Meagher County Valleys-Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass. Winter Weather Advisory until 10 AM MST Saturday for Bears Paw Mountains and Southern Blaine-Big Belt, Bridger and Castle Mountains-Cascade County below 5000ft-Fergus County below 4500ft- Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains-Hill County-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Meagher County Valleys- Northern Blaine County-Western and Central Chouteau County. Winter Weather Advisory until 5 AM MST Saturday for Elkhorn and Boulder Mountains-Upper Blackfoot and MacDonald Pass. && $$ http://www.weather.gov/greatfalls