


Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
318 FXUS65 KBOI 120918 AFDBOI Area Forecast Discussion National Weather Service Boise ID 318 AM MDT Mon May 12 2025 .SHORT TERM...Today through Wednesday night...The upper-level low will move inland across Oregon today, continuing the threat for showers and isolated thunderstorms. Showers are expected to begin across southeast Oregon later this morning behind a cold front pushing west to east. Precipitation coverage will expand eastward with the front into southwest Idaho this afternoon. The highest PoPs (6080%) will be focused across Baker, northern Malheur and Harney Counties, while lower chances extend into southwest Idaho due to elongation of the upper trough. The best dynamics and instability will remain centered over southeast Oregon this afternoon and evening, supporting thunderstorm development. A few storms may be capable of producing gusts up to 50 mph. Farther east, southwest Idaho will stay mostly dry for much of the day, though showers could develop late this evening over south-central Idaho as the front progresses. Winds will remain breezy area-wide, with gusts in the 2030 mph range. Highs today will trend slightly below normal. On Tuesday, the upper low moves directly overhead, bringing a 3050% chance of showers along with isolated afternoon thunderstorms. Tuesday will be the coolest day of the week, with valley temperatures running about 10 degrees below normal. By Wednesday, the upper low exits east of the region, with cold northwesterly flow setting in behind it. Moisture and instability look sufficient for scattered showers and a slight chance of thunderstorms over the higher terrain of southwest Idaho. Temperatures will stay on the cool side, roughly 69 degrees below normal. .LONG TERM...Thursday through Monday...Thursday a weak upper ridge will bring slightly warmer temperatures, bringing much of the area to just a few degrees below normal. Temperatures hold steady as a weak trough moves through on Friday, bringing a 20-30% chance of showers and kicking off an active pattern through Monday. A deeper trough from the Gulf of Alaska will move overhead this weekend, bringing additional precipitation. Cold air aloft and instability will also support a slight chance of thunderstorms, with the best chance on Saturday as the low moves overhead. Breezy winds are expected this weekend with enhanced gradient forcing. && .AVIATION...VFR. Precipitation returns this afternoon, with most thunderstorm activity occurring in SE OR after Mon/17Z through Tue/05Z. Thunderstorms may produce outflow gusts up to 40 kt and small hail. During this time, light showers and virga will develop in SW ID. MVFR/IFR in precipitation and mountains may be obscured. Surface winds: SW-NW 5-15 kt, becoming W-SW 10-20 kt this afternoon. Winds aloft at 10kft MSL: SW 20-35 kt. KBOI...VFR. Light showers and virga developing this afternoon. Winds becoming variable 5-10 kt this morning, increasing to 10-15 kt westerlies with gusts 25 kt Monday afternoon. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...JDS LONG TERM....JM AVIATION.....JM