


Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
842 FXUS65 KMSO 080817 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 217 AM MDT Wed Oct 8 2025 .DISCUSSION... KEY MESSAGES: - Fair weather today and Thursday - A cold, wet system will bring rain and mountain snow Saturday. - Late Saturday or Sunday, snow levels will drop causing a transition to snow. Upper level flow turns southwesterly today as a ridge of high pressure departs the region and a trough of low pressure deepens off the coast. Clear skies will persist today through Friday morning with a slight increase in winds. Cloud cover will increase on Friday as the Pacific low starts to move inland. This system will bring a wet and snowy weekend for the Northern Rockies. Snow levels will start to fall on Saturday after it starts raining earlier in the day. By Sunday morning, expect snow levels to drop below 5,000 ft across the Northern Rockies. Median snow forecasts for Monday morning include 6-10 inches of storm total snow in the Mission, Swan, and Whitefish mountains with around a foot in the higher elevations of Glacier National Park. Further south in the Bitterroot Mountains, expect 4-8 inches of new snow including Lookout and Lost Trail passes. The median forecast for Lolo Pass is 2-4 inches. High end forecasts (90th percentile) have 18-24 inches in the mountains of northwest Montana and around 12 inches in the Bitteroot mountains for storm total snows. This is the first winter system of the year that has the potential to impact travel over mountain passes. Lookout, Lost Trail, Lolo, and Marias passes are expected to be the hardest hit, but Rogers, and MacDonald passes also have a chance (10-20%) of picking up a few inches of snow. Current forecasts for Homestake Pass show a few tenths of an inch to 2 inches of snow. A major concern with snow on the passes this time of year is melting and refreezing, causing very icy conditions. Even if the snow is melting on the roads, once the sun goes down or the temperature drops just enough the roads can become icy in a matter of minutes. If you`re traveling this weekend or early next week, be prepared for winter conditions in the mountains. While ensembles agree well on the arrival of the trough and colder air, there is considerable disagreement on how it exits the region early to mid next week. Once it starts to move out of the region, it will start interacting more strongly with any tropical systems in the Atlantic basin, and currently there`s quite a bit of uncertainty in those long term forecasts, which translates to a lot of uncertainty for mid next week. && .AVIATION... Skies will remain mostly clear today. Southerly winds will increase this afternoon, focused on the southern portion of the Northern Rockies airspace. Expect gusts of 15-20 kts at KHRF and KSMN starting late morning to early afternoon. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$