


Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
542 FXUS65 KBOI 091542 AFDBOI Area Forecast Discussion National Weather Service Boise ID 942 AM MDT Wed Jul 9 2025 .DISCUSSION...The main concern later today continues to be the potential for strong outflow winds from thunderstorms. Water vapor imagery this morning shows an upper-level low centered over northern California, which is expected to track northeast across southeast Oregon and southwest Idaho this afternoon and evening. Increasing mid-level moisture and strengthening southwesterly flow, combined with steep low-level lapse rates from daytime heating, will set the stage for scattered thunderstorm development. The most favorable area for storms looks to stretch from central Harney and Malheur Counties into southwest Idaho, including the Boise Mountains and areas along the Idaho-Nevada border. The strongest storms could produce isolated severe wind gusts up to 60 mph, especially from Malheur County eastward through the Snake River Plain and into the Boise Mountains. While not everyone will see winds this strong, a broad area of 35 to 50 mph gusts looks increasingly likely across northern Malheur County, the Weiser Basin, the Treasure Valley, and into the West Central and Boise Mountains. Blowing dust will likely accompany these winds, especially at lower elevations and in more open terrain, lowering visibilities. The greatest threat for winds/blowing dust in the Boise Metro area looks to be between 4 PM and 7 PM MDT. This system isnt particularly wet, with precipitable water values in the 5060th percentile and most high-res models showing localized rainfall rates of around 0.25 to 0.50 inches per hour. While this typically wouldn`t raise flooding concerns, we`ll be keeping an eye on burn scar areas, particularly the Wapiti Burn Scar, where thresholds for debris flows and flooding are lower. Storm chances will continue through sunset across most areas, lingering through midnight in the Boise Mountains. && .AVIATION...Isolated to scattered showers and thunderstorms will develop across the area Wednesday afternoon/early evening. Gusts up to 50 kt and blowing dust reducing visibility will be possible. Surface winds: W-NW 5-15 kt through morning and early afternoon, with locally stronger winds of 30-50 kt with outflows. Winds aloft at 10kft MSL: S-SW 5-15 kt. KBOI... Isolated thunderstorms developing after 22Z with a 30% chance of terminal being impacted. Strong outflow winds are more likely. Otherwise, VFR conditions. Surface winds: Winds NW 5-15 kt with gusts to 20 kt Wednesday afternoon. Outflow winds of 30-40 kt possible (30% chance) between 23Z and 02Z. WNW winds at 8-10 kt overnight. && .PREV DISCUSSION... SHORT TERM...Today through Friday night...Water vapor satellite imagery showing an upper low centered over northern CA tonight. Showers and thunderstorms will develop out ahead of the low as it tracks through SE Oregon and SW Idaho this afternoon. The higher thunderstorm probability will stretch from central Harney and Malheur counties in Oregon into southwest Idaho from the Boise mtns to the NV border. Outflow winds will be the main threat from storms with gusts up to 60 mph possible from Malheur County eastward through the Snake Plain and Boise mtns. While not all locations will see winds this strong, a broad area of 35 to 50 mph winds is looking more likely across northern Malheur County, the Weiser Basin, Treasure Valley and W-Central/Boise mtns. Blowing dust will accompany the winds as well, especially at lower elevations. This system isn`t particularly wet (PW values in the 50-60 %tile) with majority of high res models showing 0.25-0.50"/hr rainfall. While these amounts aren`t generally a flood concern, will need to keep an eye on burn scars, especially the Wapiti, which carry lower thresholds for flood/debris potential. The chance for thunderstorms carries through sunset for most locations, lingering through midnight in the Boise mtns. Biggest changes to the forecast tonight were to increase thunderstorm chances to 30-40% in area where strong outflow winds are more likely (which also matches up with SPC`s area of Marginal Risk). Thursday and Friday will see a return to dry weather under weak troughing in NW flow. Temperatures both days will be at or slightly below normal. Daytime mixing will bring breezy conditions on Thursday with gusts of 25-35 mph in Snake Plain east of Boise. LONG TERM...Saturday through Wednesday...A strong ridge of high pressure is expected to slowly build into the area off the California coast over the weekend, returning a warming and drying trend from Saturday to early next week. Valley daytime temperatures are expected to reach the mid to upper 90s Saturday and Sunday, and close to 100 on Monday. Long-term guidances generally project an upper trough sweeping across the northwest region, but precipitation is not hinted by this system. Wednesday will see a ridge build into the area on top of the large high pressure system over the desert southwest, continuing very warm and dry conditions. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning from 3 PM this afternoon to midnight MDT tonight IDZ400-420-423-424-426. OR...Red Flag Warning from 3 PM MDT /2 PM PDT/ this afternoon to midnight MDT /11 PM PDT/ tonight ORZ670-672>674. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise DISCUSSION...JDS AVIATION.....JR SHORT TERM...DG LONG TERM....JY