554 FXUS65 KBOI 052014 AFDBOIArea Forecast Discussion National Weather Service Boise ID 214 PM MDT Fri Sep 5 2025
.SHORT TERM...Tonight through Sunday night...Showers and storms have already begun to develop in SE Oregon and along the ID/NV border this afternoon. Coverage is expected to increase to scattered by this evening, and the possibility for abundant lightning with gusty outflows has prompted the issuance of a Red Flag Warning. Precipitable water content is about at the 75th percentile, so storms could produce moderate rainfall rates. Outflow gusts up to 50 mph are possible around storms, and may travel far away from storms resulting in brief gusty winds even for areas that don`t see lightning or precipitation. The trough providing the dynamics and moisture will swing through tomorrow, supporting another day of scattered storms Saturday afternoon and evening, with largely the same storm characteristics as today, but shifted up into parts of SW Idaho and E Oregon. As the trough exits Saturday night, it will help to mix out surface smoke that is expected to persist from now through Saturday. It will also bring breezier conditions to SE Oregon and the ID/NV border as forcing increases behind the wave, potentially leading to another fire weather concern with conditions still warm and dry.
.LONG TERM...Monday through Friday...The primary low in the short term will steadily move inland Monday, centered over the Oregon coast. After which, it will stall over the PacNW coast Tuesday evening, moving over our area by Thursday evening. The overall weather change will be lowering temperatures to 10 degrees below normal by Wednesday thanks to the colder airmass around the low pressure system. However, it will also bring more moist southwesterly flow, leading to 30% precipitation chances Tuesday through Thursday. The storm mode will be mostly convective, with a focus on storm potential in the late afternoons. Minimum relative humidities will come up in the middle of next week with the moisture and lower temps.
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.AVIATION...VFR and local MVFR with smoke layers. Scattered showers and isolated thunderstorms in eastern OR and ID/NV border. Outflow gusts could be as high as 45 kt. Surface winds: variable 5-10kt, with gusts up to 20 kts in the Snake Plain this afternoon. Winds aloft at 10kft MSL: variable 5-15kt.
KBOI...VFR with minor visibility reductions due to smoke. Brief 15-25 mph gusts from distance storms possible this evening (10% chance). Surface winds SE 5-15kt, shifting to NW 5-10kt late afternoon through the evening.
Weekend Outlook...Scattered showers and thunderstorms on Saturday afternoon. Gusty outflow winds up to 45kt possible. Drier conditions on Sunday in eastern OR with lingering showers and storms over ID mountains. Breezy southwest winds Sunday afternoon, especially eastern OR and southwest ID highlands.
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.BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...Red Flag Warning until 9 PM PDT this evening ORZ670.
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SHORT TERM...JM LONG TERM....JM AVIATION.....JM
NWS BOI Office Area Forecast Discussion