Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
916 FXUS65 KBOI 060248 AFDBOI Area Forecast Discussion National Weather Service Boise ID 848 PM MDT Thu Jun 5 2025 .DISCUSSION...Weak upper trough over the interior northwestern US developed showers in central and eastern Idaho this afternoon. Skies stayed sunny in western Idaho and eastern Oregon. The trough will exit east Friday allowing a broad Pacific upper ridge to bring warmer air to our CWA through the weekend. Monday and Tuesday now look like the hottest days with high temps in the 90s in the valleys and 80s in the mountains, i.e., slightly later than previously forecast. Gradual cooling beginning late Tuesday. Also, a slight (10-20 percent) chance of thunderstorms beginning Monday afternoon. No updates. && .AVIATION...VFR with diurnal winds overnight. Some cumulus developing Friday afternoon as a weak disturbance moves through the northwest. Less than a 10% chance of showers, mainly over the mountains of central Idaho. Surface winds: Mostly variable less than 10 kt becoming W-NW 5-10 kt Friday afternoon. Winds aloft at 10kft MSL: NW-N around 10-15 kt. KBOI...VFR. Winds less than 10 kt, become NW 8-12 kt after 18Z Friday. Weekend Outlook...VFR. Building heat will result in high density altitude, especially Sunday into Monday. Generally light west to northwest winds surface and aloft. && .PREV DISCUSSION... SHORT TERM...Tonight through Saturday night...Weak troughing aloft continues to support a 20% chance of precipitation in the Central Idaho mountains, though mostly outside of our area. In eastern Valley and Boise counties the chance of precipitation is 10%, as well as a 10% chance of thunder. This is a slight reduction from this morning as the trough has progressed east slightly faster than expected. Gusty outflows up to 25 mph are possible near showers. High pressure will build in behind the trough, continuing a warming and drying trend through the short term. Temperatures warm by about 5 degrees every day, up to 10-15 degrees above normal by Saturday afternoon. The peak of the warming comes in the long term. LONG TERM...Sunday through Thursday...A strong upper-level ridge will build in across the northwest region this weekend and hold in place until Monday. The heat will peak Sunday and Monday with lower elevations reaching the upper 90s. There remains a 5-10% chance of peak afternoon/early evening temperatures reaching or exceeding 100 deg for most valley areas on those two days. There is better guidance on the arrival of an upper-level trough expected to break down the ridge Monday to Wednesday. For now, forecast guidance has a 20-30% chance of showers and thunderstorms across higher terrain Monday to Wednesday. If this system holds together as current guidance shows, would expect probabilities to increase, even at lower elevations. Thursday is mostly dry with lingering high elevation showers as a broad trough remains positioned along the West Coast, with some degree of uncertainty over the timing and arrival. After topping out around 15 degrees above normal Sunday/Monday, temperatures pull back to around 10 degrees above normal Wednesday/Thursday. Afternoon relative humidity levels are expected to remain on the lower end (10-20%) throughout the extended forecast period from Sunday to Thursday. && .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...LC AVIATION.....MC SHORT TERM...JM LONG TERM....JY