Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
642 FXUS65 KBOI 291546 AFDBOI Area Forecast Discussion National Weather Service Boise ID 946 AM MDT Fri Aug 29 2025 .DISCUSSION... PWs haven`t decreased as much as models were projecting, as this morning`s sounding has 0.79 inches which is still above the 75th percentile for this time of year. Additionally, this morning`s sounding reveals some instability already present in the atmosphere. About 83 J/kg of SBCAPE will likely rise closer to 200-400 J/kg by this afternoon as the morning inversion weakens and mixing increases. Models project a similar day to yesterday, isolated storms and showers in Baker County, ID/OR/NV border area, and now S-central ID. We`re still expecting outflow gusts up to 45 mph and moderate rainfall rates. Given a storm yesterday strengthened and likely produced 1 inch diameter hail, the same cannot be written off today in a similar environment. Conditions are still on track to warm and dry out this weekend. The other forecast highlight is the smoke from Oregon. Visible on satellite is a large plume of wildfire smoke moving across most of our forecast area. The smoke is forecast to remain over the area at least through the night, but the night time settling of the smoke favors a particularly smokey Saturday morning, including the Treasure Valley. && .AVIATION...Generally VFR. Haze from wildfire smoke through ~20kft MSL, reducing to MVFR visibility in some areas. Isolated showers/thunderstorms in e-central Oregon, and higher terrain surrounding the Snake Plain in Idaho after 20Z today. Thunderstorms capable of moderate/heavy rainfall, small hail, and gusts to 30-45 kt. Surface winds: variable up to 10 kt. Winds aloft at 10kft MSL: variable 5-10 kt. KBOI...VFR. Haze from wildfire smoke. Light SE surface winds, becoming NW in the afternoon. A brief 25 kt outflow gust from storms to the far NW this evening is possible. Weekend Outlook...VFR. Continued haze from wildfire smoke. Surface winds generally S-E 5-15 kt. && .PREV DISCUSSION... SHORT TERM...Today through Sunday night...For today, lingering mid-level moisture will support another round of afternoon and evening thunderstorms. Similar to yesterday, storms will initiate across SE Oregon and mountainous areas along the ID/OR border. Isolated stronger storms are possible, bringing winds to 45 mph brief heavy rain and small hail. Saturday and Sunday will see an amplifying upper ridge bring dry and stable conditions to the region, shutting down any potential for thunderstorm development. Temperatures will warm several degrees each day through Sunday, placing valleys in the low 90s and mtns in the low-mid 80s over the weekend. Westerly flow will continue to transport smoke from wildfires (mostly the Emigrant Fire located SW of Bend) into SE Oregon and SW Idaho. Could see some improvement over the weekend as southerly flow deflects the thicker smoke to the north and west of our area. LONG TERM...Monday through Friday...A high amplitude ridge will remain positioned over the interior western US through most of next week. Southerly flow on the west side of the ridge and a minor closed low along the CA coast will draw monsoon moisture northward into the region Tue/Wed. There are differing ideas among the operational solutions on how to handle these features, but initial thoughts would be that SE Oregon and areas along the ID/NV border are the most likely spots to see a resulting chance of thunderstorms. This threat would possibly shift into central Idaho for Wed/Thur, though confidence on these details is low. For now sticking with the NBM output which carries a 10-15% chance in these areas starting Tuesday. Temperatures hold around 5 degrees above normal under the ridge, or highs in the low 90s across lower valleys and mid 80s in mtn valleys. && .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...JM AVIATION.....JM SHORT TERM...DG LONG TERM....DG