Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
927 FXUS65 KBOI 070222 AFDBOI Area Forecast Discussion National Weather Service Boise ID 822 PM MDT Thu Jun 6 2024 .DISCUSSION...Clouds held temps down and limited thunderstorm development this afternoon, but several strong storms did form late today along and south of the ID/NV border. At 8 PM MDT KCBX radar still showed one thunderstorm in southeast Owyhee County, and scattered light rain showers northward into Elmore County. The thunderstorm may reach the western Magic Valley between 10 PM and midnight MDT according to hi-res models, but other parts of our CWA should have only clouds. Hottest days still look like Friday and especially Saturday before a weak Pacific trough comes inland with modest cooling Sunday. A 15-30 percent chance of afternoon and evening thunderstorms is indicated in southern areas Friday and Saturday, with smaller chances farther north. Best chance of rain (25-50 percent) for the whole CWA will come Sunday and Sunday evening when the Pacific trough comes in. Drier, still warm (but not hot), and breezy weather is indicated Monday through Thursday under strong westerly flow aloft. Current forecast covers that well. Possibly more interesting is a deep upper low in the Gulf of Alaska that longest-range GFS and ECM bring directly into our CWA next weekend. ECM has been showing this for several days now and if models verify we would have showery and much cooler weather, cold enough even for snow on mountains above 6000 feet. Still too far off to make a firm prediction. Just letting you know what models see. && .AVIATION...VFR with scattered-broken mid and high level clouds, decreasing overnight. Scattered showers and isolated thunderstorms south of a KBNO-KMUO-KJER line, ending by Fri/09Z. MVFR/IFR conditions within storms. Low confidence (less than 30 percent chance) of any shower/storm reaching a terminal. Stronger storms will be capable of producing gusty outflow winds to 35 kt. Surface winds: variable up to 10 kt, except gusty near storms. Winds at 10k ft MSL: SW-NW 10-20 kt. KBOI...VFR. Decreasing mid to high clouds overnight. Variable surface winds less than 10 kt overnight, becoming NW 8-13 kt Friday afternoon. Weekend Outlook...VFR, except MVFR conditions with stronger thunderstorms. Isolated to scattered afternoon/evening showers and thunderstorms near the Nevada border on Friday, portions of SE Oregon and near the ID/NV border Saturday, and all areas on Sunday. Highest confidence of convection is Sunday. Gusty outflow winds will be possible from showers and storms. Otherwise, surface winds generally W-NW 5-15 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Saturday night...The short term will be dominated by an amplifying upper ridge. Highs today will be about 10 degrees above normal, warming to 15-20 degrees above normal on Saturday. Clouds/storms today may limit surface warming in certain areas, but their extent is forecast to be limited to the ID-NV border on Friday and Saturday so confidence is higher in hot temps on these days. The rest of today will continue to be active with showers and a few storms. Outflow gusts around storms could be up to 40-50 mph, but the current radar situation seems to favor the lower end of that range if anything. Precipitation is fairly high-based, limiting precipitation on the ground and favoring virga. Storms may be directed into portion of the Snake Plain with the SW flow aloft, but they will struggle to stay together as they move out of the SW Highlands. Precipitation cuts off around midnight tonight. As mentioned previously, unsettled conditions will continue for the short term, as Friday afternoon/evening storms develop again. They are much more limited, forming mainly near the ID-NV border. Precipitation chances increase again Saturday evening ahead of a quick trough in the long term. There may be some haze or smoke south of Rome, Oregon due to a fire south of the Owyhees. LONG TERM...Sunday through Thursday...An upper level low moves inland on Sunday. With moisture already present, this injection of energy makes Sunday the most active looking day for this forecast. The trough also brings PW values in the 90th percentile, just under 1". Precipitation chances stay elevated through the day, with a 10-30% chance for lower valleys and 30-50% chance for higher terrain. While temps cool by about 5 degrees from Saturday, there will still be enough instability to support a 20% chance of afternoon/evening thunderstorms, mainly over terrain. Drier westerly flow sets in on Monday through the rest of the long term. The gradient of this flows stays fairly decent, meaning afternoon winds after Monday will be breezy. The zonal characteristic will hold our temps mostly steady at about 10 degrees above normal. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...LC AVIATION.....ST SHORT TERM...JM LONG TERM....JM