Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
231 FXUS65 KBOI 121524 AFDBOI Area Forecast Discussion National Weather Service Boise ID 924 AM MDT Wed Jun 12 2024 .DISCUSSION...Dry cold front passed through overnight with gusty northwest winds that will continue through the afternoon in the Snake Basin east of Boise. Tonight should be clear and cool with calming winds then mostly sunny and hotter again Thursday under a passing upper ridge. Latest models show enough moisture and instability for a slight chance of thunderstorms in/near Twin Falls County late Thursday and Thursday evening, already in the current forecast. The deep, cold upper low in the Gulf of Alaska is now forecast directly over our CWA Monday with much better model consistency than yesterday. Our forecast has high temps in the 60s to mid 70s Monday but latest models look at least 5 degrees colder and highs will be lowered in this afternoon`s package. NBM is among the warmer models but even it shows accumulating snow above 7000 feet in the central Idaho Mountains Monday and Tuesday. All this happens in the extended period. Current forecast is good in the short term so no updates for now. && .AVIATION...VFR and mostly clear. Surface winds: W-NW 5-15 kt, gusts 20-25 kt KBOI southeast through the Magic Valley terminals. Winds aloft at 10kft MSL: W-SW 15-30 kt. KBOI...VFR under clear skies. Surface winds: NW 7-13 kt. Gusts up to 20 kt this afternoon. && .PREV DISCUSSION... SHORT TERM...Today through Friday night...A dry cold front is moving through the CWA this morning, with gusts to 40 mph reported at KONO in the past few hours. This front was moving east through the Treasure Valley as of 2 AM MDT, and will move through the western Magic Valley between 9 AM and noon. Gusts to 30 mph will continue generally east of Mountain Home this afternoon into early this evening. Slightly cooler air will filter in behind the front, and highs today will be 5-10 degrees cooler than yesterday, but still 5-10 degrees above normal. As our upper flow turns more southwesterly tonight, in advance of a large and strong upper level low off the Canadian coast, we will see warmer air once again drawn northeast over the region. Highs Thursday will be about 5 degrees warmer than today. In addition, meso models are now indicating that sufficient moisture and instability will work into the SE corner of the CWA (roughly meaning eastern Owyhee County and the western Magic Valley) late Thursday afternoon and into the overnight hours, leading to an increase in the area of showers and thunderstorms forecast there. This moisture will move out by early Friday, and there is no chance of precipitation in the forecast for Friday or Friday night. Temps will cool back down around 5 degrees Friday compared to Thursday, and another cold front Friday night will lead to even cooler temperatures heading into the long term period. LONG TERM...Saturday through Wednesday...Models have finally come into reasonable agreement on the upper level flow over the weekend. After the front Friday night, and the passage of an associated upper level shortwave trough, much cooler air will move into the area Saturday. There will also be a slight chance of showers in the far northern higher terrain Saturday afternoon and evening. High temperatures Saturday may actually be a degree or two below normal. Breezy northwest winds will develop Saturday, and continue to a lesser extent Sunday and Monday. As heights continue to fall Saturday into Sunday, temps will continue to cool. The main part of the upper level system (initially to our northwest) will move through as a closed low Sunday night into Monday. The latest GFS has this system move directly over the CWA, but ensembles place a higher probability on passage centered just to our north. The difference is important, because the more southern track would both cool us off more and bring more precipitation than indicated in this new forecast. For now, we have a roughly 15% to 35% chance of showers and thunderstorms over the north, mainly in the higher terrain, Sunday night through Tuesday night. Temperatures will cool to 5 to 10 degrees below normal Sunday through Tuesday, then moderate to near normal Wednesday. Should the GFS track prove to be accurate, temps would be 10-20 degrees below normal Sunday through Tuesday, with precipitation spreading to all parts of the CWA. && .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...SP LONG TERM....SP