Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
413 FXUS65 KBOI 030303 AFDBOI Area Forecast Discussion National Weather Service Boise ID 903 PM MDT Sat Aug 2 2025 .DISCUSSION...A few weak showers and thunderstorms remain across southeast Oregon this evening, expected to diminish after sunset. The strongest storms earlier developed across Owyhee and southern Twin Falls Counties, producing frequent lightning, brief heavy rainfall, and wind gusts up to 55 mph. Smoke may impact sunset visibility in the Treasure Valley due to the Victory Fire, a 900-acre fire in southern Ada County. The fire was reported fully contained as of 8 PM MDT, but satellite imagery still shows a substantial amount of smoke lingering over the valley. Additional shower and thunderstorm development is expected across southeast Oregon and the west-central Idaho mountains from mid-morning Sunday through early afternoon. This activity will be driven by dynamic lift ahead of an approaching upper trough interacting with elevated instability. The best overlap of surface energy, low to mid-level shear, and upper support will be along and north of a Burns to Caldwell line, extending through Garden Valley and Yellow Pine supporting long-lived thunderstorms. The primary concern in this area will be the potential for severe outflow winds up to 65 mph, with hail and heavy rainfall also possible. Higher precipitable water values across eastern Oregon will support stronger storm cores capable of producing heavier rainfall and a deeper cold pool. This will likely lead to widespread outflow wind gusts of 30 to 45 mph, with localized gusts of 45 to 55 mph, spreading across southeast Oregon and into the Snake Plain and Boise Mountains by Sunday afternoon and evening. Blowing dust will be a concern with these winds as they track east through the Snake Plain. The current forecast captures this setup well, though additional headlines may be needed as the event approaches. && .AVIATION...VFR. Scattered showers and thunderstorms dissipating through evening. Overnight precipitation possible in SE Oregon. On Sunday, scattered afternoon showers/thunderstorms for east Oregon and central Idaho. Thunderstorms capable of 30-50 kt outflows, and heavy rain/small hail resulting in localized MVFR to LIFR conditions. Blowing dust possible Sunday evening with cold front and outflows. Mtns obscured in precip, and in vicinity of wildfires. Surface winds: light and variable overnight. Winds aloft at 10kft MSL: W to NW 5-15 kt, becoming S to SW after Sun/12z. KBOI...VFR. High density altitude Sunday afternoon. On Sunday near/after 00z, 15-20% showers/thunderstorms and strong NW winds with gusts that could reach 30+ kts. Current surface winds: light and variable overnight becoming S to SE Sunday morning. && .PREV DISCUSSION... SHORT TERM...Tonight through Monday night...Thunderstorms will dissipate this evening with sunset leaving dry conditions overnight for most zones. The southern/eastern Blues in Oregon will carry a 10-15% chance of showers overnight as an upper trough pushes onto the Pac NW coast. Shower and thunderstorm development will increase across SE Oregon and west-central Idaho mtns from mid-morning Sunday through early afternoon as the dynamic lift in advance of the upper trough taps into elevated instabiltiy. Areas along and north of a line from Burns to Caldwell up to Garden Valley and Yellow Pine is where we see the best overlap of available surface energy, low-mid level shear, and upper dynamics. The main storm threat from in this area will be potentially severe outflow winds (up to 65 mph) with hail and heavy rain also poissible from storms. The outflow pool that takes shape over e-central Oregon will flush eastward Sunday evening, bringing widespread wind gusts of 30-45 mph with more localized 45-55 mph gusts as it rolls through SE Oregon and the Snake Plain in SW Idaho. These winds will pick up dust along the way and have kept blowing dust wording in the forecast. A low chance of showers and thunderstorms hangs on Sunday night across Baker County and the w-central Idaho mtns as the upper trough crosses into central Idaho. Daytime heating will increase the area of shower/storm potential with a 20-40% chance of showers and thunderstorms wrapping around the Snake Plain by Monday afternoon. High temperatures are 8-12 degrees cooler than Sunday and will be accompanied by breezy northwest winds. LONG TERM...Tuesday through Saturday...West-southwest flow Tuesday and Wednesday will keep temps hot, though about normal, and conditions dry through Wednesday afternoon. A longwave trough is expected to pass north on Wednesday night, bringing increased cloud cover and some possible precipitation and frontal wind. Though, it does not appear too significant in recent model runs and most of the moisture is north of us. A 10-20% chance of precipitation exists across our northern areas through early Friday. Friday evening and Saturday a blocking high builds over the northern Pacific, putting us under cooler northwesterly flow. While conditions remain dry, we`ll be about 5-10 degrees below normal by the end of the week. && .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 DISCUSSION...JDS AVIATION.....CH SHORT TERM...DG LONG TERM....JM