Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
941 FXUS65 KBOI 260928 AFDBOI Area Forecast Discussion National Weather Service Boise ID 328 AM MDT Wed Jun 26 2024 .SHORT TERM...Today through Friday night...Mid and high level moisture has come in from the south with radar showing rain echoes in the southern Owyhee Mountains and along the NV/OR border at 3 AM MDT. Lightning has been detected near Denio/NV along the NV/OR border. Latest models develop a swath of showers this morning from southern Harney County through central Malheur County, into the Lower Treasure Valley, Upper Weiser River Valley, and Boise Mountains, with scattered lighter showers elsewhere in our CWA. Instability for thunderstorms is forecast to stay south of 44N this morning.However, isolated to scattered strong thunderstorms will develop this afternoon on the Idaho side as instability rapidly increases, with gusts up to 50 mph along with small hail. Greatest instability is forecast in the Upper Treasure Valley, Boise Mountains, and throughout south-central Idaho. Meanwhile, the air mass in Oregon will become become relatively stable this afternoon, but southwest winds will increase to 20 to 30 mph with gusts to 35 mph in Harney and Malheur Counties. These winds will be ahead of a cold front that will move through eastern Oregon this evening and western Idaho tonight. This will lead to significant cooling Thursday through Friday as the associated upper trough moves through. High temps in the 80s to mid 90s today will be replaced by upper 60s and 70s Thursday, and 70s to lower 80s Friday, along with lighter winds and mostly sunny skies. Low temps will also be noticeably cooler Friday morning, 40s to lower 50s in the valleys and mid 30s to mid 40s in the mountains. A slight chance of showers and afternoon thunderstorms will linger in the northern-most mountains of our CWA as the upper trough passes by, .LONG TERM...Saturday through Wednesday...The upper level flow will transition to southwesterly on Saturday ahead of the next Pacific trough. This will promote hotter temperatures, reaching roughly 10 degrees above normal. Clouds will increase throughout the day as a cold front arrives late Saturday into Sunday. This front will initiate breezy winds, cooler temperatures, and a 15-35% chance of showers and thunderstorms on Sunday. Daytime instability for thunderstorm development will become greatest over southwest/central Idaho, especially for the higher terrain. Dry conditions with breezy winds are forecast for Monday, along with temperatures reaching near to 5 degrees above normal Monday through Wednesday. && .AVIATION...VFR with mid/high level clouds. Isolated to scattered showers/thunderstorms across SE Oregon and SW Idaho, continuing through Wed afternoon. Outflow gusts 30-45 kt possible. Meanwhile, hot daytime temperatures will increase density altitude today. Surface winds: SE to SW 5-15 kt. Increasing to 10-20 kt with gusts to 25-30 kt in E Oregon and near NV/ID border Wed afternoon. Winds aloft at 10kft MSL: SW 15-30 kt. KBOI...VFR with mid/high level clouds. A 40% chance of showers/thunderstorms hitting terminal between 26/12Z and 27/00Z, with outflow gusts of 30-45 kt possible. Surface winds outside of storms: SE 5-15 kt, transitioning to NW this evening. Hot daytime temperatures will increase density altitude today. && .FIRE WEATHER...Instability for thunderstorms is now forecast to stay south of about 44N through the morning so the Red Flag Warning for lightning is being delayed in the Payette NF until noon MDT. However, instability will rapidly increase this afternoon and isolated to scattered strong thunderstorms will develop on the Idaho side, with gusts up to 50 mph along with small hail. Greatest instability and strongest storms are forecast in the Boise and Twin Falls BLM areas, and the Boise NF. Meanwhile, the air mass in the Burns and Vale BLMs in Oregon will become more stable this afternoon and thunderstorms should end there. However, southwest winds will increase to 20 to 30 mph with gusts to 35 mph, and that along with low humidity will maintain the Red Flag Warning in those areas until 8 PM PDT. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning from noon until 9 PM MDT this evening IDZ401-402. OR...Red Flag Warning until 9 PM MDT /8 PM PDT/ this evening ORZ636-637. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...LC LONG TERM....SH AVIATION.....SH FIRE WEATHER...LC