066 FXUS65 KBOI 150903 AFDBOIArea Forecast Discussion National Weather Service Boise ID 303 AM MDT Mon Sep 15 2025
.SHORT TERM...Today through Wednesday night...A few showers are expected to linger this morning across the west-central Idaho mountains as the upper-level trough continues its slow eastward progression over the northern Rockies. This will maintain a threat for showers and thunderstorms (20% chance) through the afternoon. The primary impact will be cooler, northwesterly flow across the area, which will keep temperatures about 7 degrees below normal. We are also expecting breezy westerly surface winds across the Snake River Plain. An upper-level ridge will build into the region on Tuesday, allowing temperatures to moderate back to near normal. The ridge will remain in place through Wednesday, with temperatures warming to near 5 degrees above normal.
.LONG TERM...Thursday through Monday...An upper-level ridge will continue to build across the region on Thursday, bringing clear skies and slightly above-normal temperatures, with highs expected to be about 5 degrees above normal. On Friday, the ridge axis will gradually shift eastward, allowing for the return of a south-to-southwesterly flow aloft. This pattern change is driven by an upper-level trough off the coast of California. As the ridge continues to weaken, the chance of precipitation will slowly increase on Friday afternoon and then rise further through Saturday and Sunday. There remains large variation in long-range model solutions for how this pattern evolves. Therefore, confidence is low in any specific details beyond this period.
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.AVIATION...Isolated showers continuing in west central mountains of Idaho through this afternoon for brief MVFR/IFR. Mtns obscured in precip and low clouds. Patchy mountain-valley fog and low stratus ending after sunrise. Otherwise, VFR. Surface winds: Generally W-N 5-15 kt. Winds aloft at 10kft MSL: W to NW 10- 25 kt.
KBOI...VFR, becoming mostly clear Monday morning. Surface winds: NW 5-10 kt.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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SHORT TERM...JDS LONG TERM....JDS AVIATION.....JDS
NWS BOI Office Area Forecast Discussion