870 FXUS65 KBOI 081023 AFDBOIArea Forecast Discussion National Weather Service Boise ID 423 AM MDT Mon Sep 8 2025
.SHORT TERM...Today through Wednesday night...A well defined upper level trough remains off the northern CA coast on satellite this morning. Southwest flow continues today with a dry slot over the area today. This feature will provide breezy southwest winds this afternoon over the higher terrain of eastern OR and southwest ID. Temperatures will be around 5 degrees above normal today. The upper level trough slowly moves inland on Tuesday with increasing clouds and cooler temperatures. Isolated showers and thunderstorms develop early Tuesday morning across the Idaho zones with a 10-20 percent chance of precipitation, and develop over eastern OR later in the day. The trough moves inland over southcentral OR on Wednesday with a 40-60 percent chance of precipitation and a 10-20 percent chance of thunderstorms. The NAM and Canadian are much deeper with the upper level trough and have much higher amounts of precipitation wrapping around the system, while the EC and GFS are less impressive. Temperatures lower to around 10 degrees below normal on Wednesday.
.LONG TERM...Thursday through Monday...The trough will be slow to move across the area through Friday, with a 20-50 percent chance of showers and a 10-20 percent chance of thunderstorms through Friday. Drier and slightly warmer conditions on Saturday between systems. Another trough moves through the area on Sunday and Monday with slightly cooler temperatures and a 20-40 percent chance of precipitation. Temperatures will be around 10 degrees below normal on Thursday, warming to near normal by Saturday, and 3-5 degrees below normal Sunday and Monday.
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.AVIATION...VFR. Isolated showers and thunderstorms NW of KBKE KBNO this afternoon. Surface winds: SW 5-15kt, strongest over eastern OR and SW ID highlands, becoming NW 10-20kt in eastern OR in the evening. Winds aloft at 10kft MSL: SW 10-20kt.
KBOI...VFR. SE 5-10kt, becoming NW 5-10kt during the afternoon.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None.
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NWS BOI Office Area Forecast Discussion