Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
989 FXUS65 KMSO 072124 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 224 PM MST Fri Nov 7 2025 .DISCUSSION... KEY MESSAGES: - Snow showers over mountains and passes possible into this evening. - High pressure builds this weekend; risk for fog and low clouds Sunday and Monday mornings. Breezy and showery conditions continue this afternoon behind the passage of a cold front, which occurred early this morning. Shower activity will primarily be focused over the higher terrain and may impact high elevation mountain passes at times with a light dusting of snow. Breezy westerly winds will continue into the evening. The wind has brought drier air into the valleys, which will likely help limit the extent of fog/stratus development into Saturday morning. Locations that do see clearing tonight can expect temperatures to drop into the upper teens to 20s by Saturday morning. High pressure begins to build over western Montana and north central Idaho for the weekend. With a stable airmass over the region, the development of valley inversions is anticipated. While mountains and the higher terrain will see periods of sun and above normal temperatures, valley locations will likely see the development of fog and low clouds (stratus), especially across portions of northwest Montana, west-central Montana and north- central Idaho. This becomes more likely Sunday into Monday when the ridge reaches peak strength. Areas with persistent fog will be 5-10 degrees cooler than currently forecast, though pinpointing specific locations remains difficult. Locally dense fog may develop in the early morning hours, which could cause difficult driving conditions due to lower visibility and ice. Forecast models are generally in agreement that the ridge will begin to flatten around Tuesday next week. This will increase winds over the higher terrain and may help to weaken any inversions that have developed over the weekend. In addition, forecast models continue to show a decaying plume of Pacific moisture will move overhead, leading to showers and light high elevation snow (6000-7000 ft). && .AVIATION... Breezy westerly winds will continue into this evening across all of western Montana and north central Idaho, with gusts 20 to 25 kts fairly widespread. In addition, ongoing mountain showers will cause locally lowered visibility and ceiling, obscuring terrain. Winds and shower activity will decrease after sunset this evening. Developing high pressure will allow for more stable conditions to set up over the region into the weekend. Drier air that mixed down with afternoon winds this afternoon, should keep the development of widespread fog at bay through Saturday morning. However, localized valley fog cannot be ruled out, especially across northwest Montana (KGPI) and north central Idaho. && .AIR STAGNATION...Stable conditions will develop over western Montana and north central Idaho this weekend as high pressure influences the region. The ridge will likely reach peak strength Sunday into Monday, before flattening and introducing some wind aloft and a plume of decaying Pacific moisture on Tuesday. Valley fog and low stratus is likely to develop, especially Sunday into Monday and may lead to degrading air quality. Air stagnation advisories are not currently anticipated due to the relatively warm and early season nature of this event, with mixing heights generally lowering to around 1500 to 2000 ft AGL. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$