Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
241 FXUS65 KBOI 181543 AFDBOI Area Forecast Discussion National Weather Service Boise ID 943 AM MDT Thu Jul 18 2024 .DISCUSSION...Widespread smoke is causing poor air quality and reduced visibility near Burns, OR and in valleys in the Boise Mountains this morning. Hot and above normal temperatures will continue to affect the region today with a low potential (10-20% chance) for thunderstorms near the ID-NV border and over the Boise Mountains this evening. Gusty outflows and frequent lightning are the main concerns with these thunderstorms. Another monsoonal push is still expected Friday night, although confidence is low in the extent of showers pushing north over the Central ID Mountains. Westerly winds will pick up across the region this evening, especially as the downslope flow increases overnight. No updates necessary. && .AVIATION...Smoky, local visibilities to MVFR/IFR mainly over KBNO. High density altitude due to heat. Isolated to scattered thunderstorms during the afternoon, mainly south of KTWF KJER. Surface winds variable 5-10 kt, becoming W-NW 5-15 kt during the afternoon. Gusty erratic outflow winds up to 45 kt in vicinity of thunderstorms near KTWF KJER. Winds aloft at 10kft MSL: SW 5-15 kt. KBOI...VFR. Smoky. High density altitude due to heat. Surface winds SE 5-10kt, shifting to NW 5-10kt during the afternoon. Weekend Outlook...Smoke reducing visibilities. Isolated thunderstorms on Saturday afternoon mainly near NV border, then isolated thunderstorms Sunday afternoon mainly over the higher terrain. && .PREV DISCUSSION... SHORT TERM...Today through Saturday night...A weak shortwave over northern ID will continue to move northeast today, and the upper level ridge will reamplify. Amplification of the ridge supports a couple of degrees of warming today. Some monsoonal moisture over NV will move northward into the southwestern Idaho highlands this afternoon, mainly over Owyhee County and southern Twin Falls County. Storms will be capable of gusty erratic outflow winds up to 50 mph. The ridge will continue to strengthen and expand over southwest Idaho and southeast Oregon through Sunday, with another prolonged heat wave. A weak shortwave will move across eastern OR and southwest Idaho on Friday morning, enhancing the threat of thunderstorms, mainly on the Idaho side through late Friday afternoon. Thunderstorms will be high-based with little rainfall and result in additional fire weather concerns. Storms will also be capable of gusty outflow winds. Smoke will persist across the area. Excessive heat warnings remain in effect. Temperatures will warm to near record levels, around 10-15 degrees above normal by Sunday. LONG TERM...Sunday through Thursday...Smoky conditions continue. Upper level ridge will strengthen and reach peak amplitude over southwest Idaho and southeast Oregon Sunday and Monday. This will bring hotter temperatures to the area, with many lower valley locations reaching 105 to 110 degrees through Tuesday. Record highs will likely be broken in many areas during this time period, however smoke may keep temperatures a few degrees below forecast depending on how thick the smoke is. Limited moisture will remain trapped within the upper level ridge, resulting in a 10-20% chance of showers and thunderstorms across the higher terrain on Sunday and Monday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning until 9 PM MDT this evening IDZ423-426. Excessive Heat Warning until noon MDT Saturday IDZ012-014-033. Excessive Heat Watch from Saturday afternoon through Tuesday evening IDZ012-014-016-030-033. OR...Excessive Heat Warning until noon MDT Saturday ORZ064. Excessive Heat Watch from Saturday afternoon through Tuesday evening ORZ062>064. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...SA AVIATION.....SA SHORT TERM...KA LONG TERM....KA