651 FXUS65 KBOI 220236 AFDBOIArea Forecast Discussion National Weather Service Boise ID 836 PM MDT Sun Sep 21 2025
.DISCUSSION...Showers and thunderstorms are weakening this evening and remaining activity will continue to diminish through midnight. Gusty northwest winds to 40 mph already blowing across SE Oregon this evening and they will push through the lower Snake Plain early tonight, with the strongest winds (to 35 mph) from the Snake River to the ID/NV border. While open terrain is breezy overnight, sheltered mtn valleys will see lighter winds and possible fog formation. Have updated the wind/wind gusts for tonight.
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.AVIATION...Isolated showers and thunderstorms through 06Z tonight. Local IFR in mtn valley fog Monday morning. Otherwise VFR with increasing smoke across e-central Oregon bringing some reduction in visibility Monday afternoon. Surface winds: NW 5-15 kt. Locally 10-20 kt with gusts 30 kt KBKE-KONO-KMUO through 12Z Monday morning. Winds aloft at 10kft MSL: W-NW 10-20 kt.
KBOI...VFR. NW surface winds through Monday evening.
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.PREV DISCUSSION... SHORT TERM...Tonight through Tuesday night...A cold front continues to move through the region today with scattered showers and isolated thunderstorms over the Idaho side. The cold front will bring breezy conditions this afternoon with wind gusts of 20-30 mph from the west-northwest. The thunderstorm threat appears to be from Rome OR to Boise and areas east right now with the threat ending west of this line. Temperatures cool to around 5 degrees below normal on Monday. Breezy conditions continue on the Idaho side on Monday with gusts of 20-30 mph during the afternoon in the Treasure Valley and Magic Valley. A ridge rebuilds over the area on Monday with warm and dry conditions. Temperatures Tuesday warm to around 5 degrees above normal with dry conditions.
LONG TERM...Wednesday through Sunday...An upper-level ridge will be well in place Wednesday into Thursday as an omega block pattern sits over the mainland United States. Temperatures will be 5 to 10 degrees above normal. Midday Thursday into evening, an upper-level low will move east into the Desert Southwest, creating more zonal flow conditions over the area. Over the weekend, an upper-level trough system off the coast of Alaska will begin to dictate flow over the Pacific Northwest. Multiple rounds of shortwaves troughs embedded in the flow will attempt to move through the area, however limited moisture will inhibit any attempts at convection. Once this low gets close to moving inland, deterministic guidance vary considerably. Ensembles continue to struggle with the evolution of this trough, which would drastically determine how cool and wet conditions will become once it moves onshore.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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DISCUSSION...DG AVIATION.....DG SHORT TERM...KA LONG TERM....CH
NWS BOI Office Area Forecast Discussion