FXUS65 KBOI 090257 AFDBOI Area Forecast Discussion National Weather Service Boise ID 857 PM MDT Thu May 8 2025 .DISCUSSION...An amplifying ridge and southwest flow aloft will direct warmer air into the region on Friday with valley highs in the 80s, which is around 5-10 degrees warmer than today. Conditions will remain dry, along with light winds. No updates. && .AVIATION...VFR with high clouds filling in this evening. Surface winds: variable less than 10 kt tonight, becoming SE at 5-10 kt Friday morning. Winds aloft at 10kft MSL: SW 15-25 kt. KBOI...VFR. VRB winds 4-6 kt tonight, shifting E-SE 5-8 kt Friday morning. Weekend Outlook...Saturday will be warm and dry with increasing clouds. Showers and thunderstorms possible (15-30%) over the Boise Mountains and ID/NV border late afternoon into evening. On Sunday afternoon, a cold front will move from SE OR into SW ID, bringing a slight chance of showers and thunderstorms with gusty westerly winds, lowering ceilings, and mountain obscuration. && .PREV DISCUSSION... SHORT TERM...Tonight through Saturday night...The slight cooling behind last night's cold front will end tonight, and Friday will be 8 to 10 degrees warmer than today, with Saturday equally warm in Idaho, but starting to cool in Oregon. Friday and Saturday should be the warmest days so far this year, and not likely to occur again until at least May 22. The warming will be due to an upper ridge amplifying over the Great Basin, and increasing southwest flow aloft as a Pacific upper trough/low approaches the coast. Skies will stay clear through Friday. After that the trough will gradually transport moisture into our CWA, leading to the first chance (15-30 percent) of high-based thunderstorms late Saturday and Saturday night in southern and central Idaho, even before eastern Oregon (closer to the trough). Winds will be light through Saturday morning, then increase to 20 to 30 mph in southeast Oregon Saturday afternoon and evening. LONG TERM...Sunday through Thursday...An upper level low will move into the region on Sunday afternoon, bringing temperatures 15-25 degrees cooler for the next week. The associated cold frontal passage will bring a slight chance of thunderstorms on Sunday evening, with the highest instability currently forecast over southwest Idaho. Breezy winds will increase Sunday afternoon as well, with gusts up to 40-50 mph near the Nevada border. The upper level low will then meander slowly to our east through the beginning of next week, bringing a shift to cooler and wetter weather. Precipitation chances are about 50-70% over higher terrain and down to about 20-30% over lower elevation valleys Monday-Wednesday. Cooler temperatures will also bring mountain snow, with snow levels dropping to about 5500-6500 feet overnight on Monday and Tuesday. Accumulations will be light and wet, but higher elevation passes (i.e. Mores Creek/ Banner Summit) could see light snow in the early morning hours on Monday and Wednesday. The upper level low will then move east, bringing northerly flow on Wednesday and Thursday, and lingering precipitation over high terrain in Southwest Idaho. Forecast models remain in good agreement with the pattern evolution through Wednesday, with some variation in precipitation amounts and location by the middle of next week. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise DISCUSSION...BW AVIATION.....JY SHORT TERM...LC LONG TERM....SA