169 FXUS65 KBOI 140242 AFDBOIArea Forecast Discussion National Weather Service Boise ID 842 PM MDT Sat Sep 13 2025
.DISCUSSION...A potent cold front will move through the area on Sunday morning in eastern OR and southwest ID around midday. This front will bring showers and scattered thunderstorms. Gusty outflow winds up to 50 mph possible in the vicinity of thunderstorms along the cold front. Gusty northwest winds will follow the front into the evening. Current forecast is on track with no updates.
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.AVIATION...Scattered showers and thunderstorms moving W to E Sunday morning through evening. Storms capable of MVFR/IFR conditions, mountain obscuration, gusty outflow winds up to 45 kt, small hail, and heavy rain. Otherwise, VFR. Smoke layers aloft, improving Sunday. Surface winds SE-SW 5-15 kt in the morning, becoming W-NW 10- 20 kt in the afternoon and evening. Winds aloft at 10kft MSL: SW 10- 25 kt.
KBOI...VFR and smoke layers aloft. Surface winds: SE 5-15 kt overnight, becoming NW 10-15 kt gusts to 20-25 kt after Sun/17Z with cold front. A 30% chance of showers/thunderstorms Sunday afternoon. Outflows from distant storms may travel to KBOI in the afternoon. Blowing dust and gusts to 25-40 kt with outflows.
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.PREV DISCUSSION... SHORT TERM...Tonight through Monday night...A relatively quiet evening tonight is in store, outside of isolated thunderstorms over the central Idaho mountains. An upper trough is approaching from the west and will move into the region on Sunday, bringing increasing chances for showers and thunderstorms. Showers will begin in eastern Oregon Tuesday morning, with perhaps even a few into the Treasure Valley in the morning hours as well. The peak of thunderstorm activity will occur during the afternoon along the I- 84 corridor into southwest Idaho, eventually spreading into the central Idaho mountains by early evening. Gusty winds to 50 mph and small hail will accompany the strongest storms. With seasonably high precipitable water values in place (near 90th percentile), hourly rainfall rates could approach 0.5" with the strongest storms. A localized flooding threat near burn scars, but rates generally appear to be below significant thresholds. This activity will continue shifting eastward into Sunday evening, persisting over the Idaho mountains into the late evening hours as the parent system stalls. A quieter day is in store for Monday, with temperatures in the low 70s.
LONG TERM...Tuesday through Saturday...As the low pressure shifts east, a ridge builds over the area and lasts through Thursday. During this period, the area will see mostly sunny skies and a return to near-normal temperatures. Wednesday temperatures rise to 5 degrees above normal before a weather change Thursday. A complex synoptic pattern sets in Thursday, with a trough axis extending over the west coast, with possibly two closed lows to the north and south of our area. Models disagree on the exact position, but cooler weather with increasing clouds and a slight chance of showers Friday and Saturday is in store. Temperatures cool back down to near normal Thursday through Saturday.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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DISCUSSION...KA AVIATION.....SH SHORT TERM...JR LONG TERM....JM
NWS BOI Office Area Forecast Discussion