Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
026 FXUS65 KMSO 090909 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 309 AM MDT Thu Oct 9 2025 .DISCUSSION... KEY MESSAGES: - Warm temperatures continue into Friday. - Increasing confidence for widespread mountain snow late Saturday into early next week. - Growing risk for a strong cold front, with valley snow chances across northwest Montana Monday into Tuesday. A large ridge of high pressure, centered over the Central Rockies will maintain warm and dry conditions across the area today. South-southeast are expected with a surface high east of the Divide and a thermal trough in central Idaho/eastern Washington. GOES Satellite imagery shows a large closed low off the OR/WA coast this morning. Forecast models project this low to slowly move inland the next couple of days, with increasing mid-upper level cloud cover in southerly flow beginning Friday. Moisture and instability will increase across north-central Idaho with showers, and perhaps a thunderstorm or two forming across Idaho County Friday late afternoon/evening. This broad low will move across the Northern Rockies Friday night into Saturday, with a cold front bringing a stark cooling trend, along with widespread shower activity and precipitation. As this trough moves inland, a second system embedded within northerly flow will dive south from British Columbia and Alberta. Those planning to head into the backcountry should prepare for cold and raw conditions, with snow covered roads above 5,000 feet by Saturday night. The threat for winter driving conditions across area mountain passes increases early Sunday morning. Forecast models are coming into stronger agreement with a stronger cold front moving along and west of the divide into northwest Montana late Sunday into Monday. Snow levels have trended lower with recent model runs, with a 50-60% chance for valley snow along the US-93 corridor from the Flathead Valley northward to the Canadian Border. Valley areas in the Kootenai/Cabinet Region and Mission Valleys see probabilities near 20-25% for valley snow. This risk for valley snow is being driven by the intersection between cold air digging southward from Canada and Pacific moisture within south-southwest flow aloft. Confidence is higher for widespread snow in Glacier Park Region, with a >80% chance for 4 inches or more. The main piece of uncertainty within model guidance is the track of the secondary low as it moves southward towards the Northern Rockies. Roughly half of ensemble members track the low across central WA/OR, with a favorable feed of moisture overrunning the cold air moving across the divide, while the other half track the low further west, leading to a drier, but still cold solution across northwest Montana. Stay tuned! && .AVIATION...South-southeast winds will develop across the Northern Rockies airspace today with a surface high centered east of the Divide. Gusts up to 15kts are expected along the divide and in Lemhi County. Waves of high clouds will move south to north through the airspace through this afternoon and evening. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$