325 FXUS65 KBOI 242006 AFDBOIArea Forecast Discussion National Weather Service Boise ID 206 PM MDT Wed Sep 24 2025
.SHORT TERM...Tonight through Friday night...Persistence through Thursday under high pressure aloft. Upper low in Calif will make a brief turn northward tonight then southward again Thursday with no effect on our wx. Changes begin Thursday night when a Gulf of Alaska upper trough moves onto the northwest coast and pushes a dry surface cold front through our CWA early Friday morning. Increased mixing at low levels will slightly moderate (i.e., raise) low temps in the normally colder valleys Friday morning. Post-frontal west winds will bring cooler air Friday with high temps 8 to 10 degrees lower than Thursday. The upper trough and cooler air mass will already be on their way out by Saturday morning.
.LONG TERM...Saturday through Wednesday...The closed upper low in southern CA/NV is expected to stall behind a broad ridge over the upper Great Basin and southern ID/OR through Saturday. This ridging will continue slightly warmer than normal temperatures for the area on Saturday and Sunday, with valleys seeing peak temperatures in the lower 80s for both days. Through Sunday, this upper low is expected to trek NE`ward as a longwave trough and steer some remnant monsoon moisture into the area, bringing a 10-15% chance of showers Sunday afternoon/ evening and a cooling trend throughout next week. Monday through Wednesday will see a strong and large upper low off the Gulf of Alaska steer into the Pacific NW region, bringing rounds of showers and thunderstorms throughout the area early next week until Wednesday. As of now, guidances indicate the higher chances of thunderstorms on Monday and Tuesday, mainly for higher elevations.
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.AVIATION...VFR with clear skies. Surface winds: E-SE 5-15 kt. Winds aloft at 10kft MSL: S-SE 5-10 kt.
KBOI...VFR with clear skies. Surface winds: SW up to 10 kt this afternoon and early evening.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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SHORT TERM...LC LONG TERM....JY AVIATION.....JY
NWS BOI Office Area Forecast Discussion