FXUS65 KMSO 052039 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 139 PM MST Mon Jan 5 2026 .DISCUSSION... KEY MESSAGES: - Snow Transition Underway: Showers will transition to primarily snow for valley floors through tonight as a cold front pushes south across the region. - Significant Mountain Snow (Tue-Wed): A potent winter storm will impact mountain passes Tuesday afternoon through Wednesday morning. Lookout Pass remains the bullseye with an 80% chance of over 8 inches of snow. - Increased Valley Snow Potential on Thursday: Model confidence is growing for a secondary trough on Thursday, which looks to be the best chance for widespread, accumulating valley snow this week. The primary story for the rest of today is the falling snow levels. As the cold front pushes through most of the precipitation will transition to snow by this evening. While tonight's snow will largely be a nuisance accumulation for most valleys (generally an inch or less), icy conditions are possible this evening into Tuesday morning. The main event begins Tuesday afternoon. A surge of deep Pacific moisture will result in heavy snow for mountain passes, particularly along the Idaho/Montana border. Mountains: Winter Weather Advisories and Winter Storm Warnings are now effect for the Northern Clearwater Mountains, Kootenai/Cabinet, Lower Clark Fork, and Glacier regions. Lookout Pass is expected to see significant impacts, with an 80% chance of seeing over 8 inches of snow in 24 hours. Valleys: Northwest Montana (Yaak, Troy and Heron) could see substantial valley snow, with 4 to 8 inches possible by Wednesday morning. Most other valleys will see a more modest 1 to 3 inches during this period. Gusty west-to-southwest winds will accompany the frontal passage on Wednesday, which may create localized areas of blowing snow on mountain passes and reduce visibility significantly. Model guidance is coming into much better agreement regarding the Thursday trough. Previous model runs showed a flatter, weaker system, but recent cluster analysis now favors a deeper and more organized trough dropping into the Northern Rockies. This evolution would provide the necessary lift and cold air reinforcement to produce meaningful valley snow across the entire region. The flow pattern is favorable for snow bands which can bring periods of enhanced snowfall. There has also been a trend for snow to linger through Friday morning. By the weekend, models are in high agreement that a ridge of high pressure will build over the region. While this ends the active snow cycle, it will likely lead to the return of valley inversions, stagnant air, and persistent morning fog. && .AVIATION...A trough and cold front moving through the region is causing widespread cloud cover showers this afternoon. As the cold front moves across the region today, snow levels will drop, causing showers to turn to primarily snow by 06/0300Z. High- resolution models agree that precipitation this evening will be focused from north-central Idaho through west-central Montana, where visibility reductions are expected in snow (IFR/MVFR). Furthermore, high dewpoints and evening showers point to increased potential for valley fog and mist to return overnight, especially in areas that see temporary breaks in cloud cover. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory from 5 PM this afternoon to 8 AM MST Tuesday for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...Missoula/Bitterroot Valleys. Winter Weather Advisory from noon Tuesday to 11 AM MST Wednesday for Kootenai/Cabinet Region. Winter Weather Advisory from 5 PM Tuesday to 11 AM MST Wednesday for West Glacier Region. Winter Storm Warning from 5 PM Tuesday to 11 AM MST Wednesday for Lower Clark Fork Region. ID...Winter Storm Warning from 11 AM Tuesday to 10 AM PST Wednesday for Northern Clearwater Mountains. Winter Weather Advisory from 4 PM this afternoon to 7 AM PST Tuesday for Orofino/Grangeville Region...Southern Clearwater Mountains. && $$