Area Forecast Discussion
Issued by NWS Missoula, MT
Issued by NWS Missoula, MT
461 FXUS65 KMSO 150805 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 205 AM MDT Sun Sep 15 2024 .DISCUSSION...Satellite imagery early this morning shows a subtle circulation over the coast of British Columbia near the U.S. border. This feature is sending moisture into the Northern Rockies from the southwest. Moist southwesterly flow will keep showers and thunderstorms in the forecast through Monday while the aforementioned circulation deepens over the West Coast. Instability will increase on Monday, bringing chances for thunderstorms up to about 30% for north-central Idaho and Montana south of and along I-90. Threats from storms on Monday will primarily be heavy rain and gusty outflow winds to about 40 mph. The West Coast trough forms a closed low and moves into the Great Basin on Monday night, pushing moisture into the Northern Rockies from the south. Precipitation will become more widespread on Tuesday and last through Wednesday as the low moves north. Chances for a half inch of rain by Wednesday evening are more than 60% over the vast majority of the Northern Rockies. The lower Salmon/Clearwater valleys, as well as the northwest corner of Montana near Yaak will see a little less. The higher terrain along the Continental Divide and the Clearwater range have about a 60-70 percent chance at an inch or more of precipitation. Two inches will not be out of the question in the Swans, Flathead, and along the Divide, especially in Glacier National Park. Those recreating in the backcountry should be prepared for a wet week with temperatures below normal and chances for snow above about 8,000 feet. Most longer range ensemble solutions show cooler, wetter weather to persist into next weekend. && .AVIATION...A fast-moving disturbance will bring chances for showers to most terminals later this morning and this afternoon. Cloud cover will persist through Monday ahead of a significant rain event midweek. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$