Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
735 FXUS65 KBOI 081651 AFDBOI Area Forecast Discussion National Weather Service Boise ID 951 AM MST Sat Nov 8 2025 .DISCUSSION...A highly amplified upper ridge will remain over the western US through the weekend, resulting in dry conditions under mostly clear skies. This will also promote warming aloft, which will transfer to mountain sites by adding 3 to 5 degrees to high temperatures each day. The lower valleys will be slower to warm, with little change in temperatures from yesterday due to the inversion setting up today. Monday will see the ridge get flattened as an upper trough tracks through the Idaho panhandle. This could be enough to help weaken the lower valley inversion. Highs will be around 10 degrees above normal on Monday, except across the lowest elevations where what remains of the inversion will hold highs closer to normal. No updates needed at this time. && .AVIATION...VFR. Surface winds: Variable under 10 kt. Winds aloft at 10kft MSL: W-NW 5-15 kt. KBOI...VFR with winds less than 10kt. Sunday Outlook...VFR under mostly clear skies. Surface winds: E-SE up to 12 kt. Winds aloft at 10kft MSL: Variable 5-15 kt. && .AIR STAGNATION...High pressure aloft will bring a period of more stagnant conditions to the region next week. A temperature inversion will lower mixing heights to between 2-3kft AGL Sunday, possibly dropping below 2kft AGL Monday and continuing through Wed/Thur. There could be some improvement late Monday into Tuesday with passage of a weak cold front. Light winds will accompany lower mixing heights. The dry air mass and lack of snow cover and will limit fog development. && .PREV DISCUSSION... SHORT TERM...Today through Monday night...An upper ridge will amplify over the western US through the weekend. This will result in dry weather under mostly clear skies across our region. Warming aloft will transfer to mountain sites which add 3 to 5 degrees to high temperatures each day. Lower elevations will lag, with little change in temperatures from yesterday to today, then several degrees of warming into Sunday. Monday will see the ridge get flattened as an upper trough tracks through the ID panhandle. Models have retreated further north with precipitation accompanying this system so rain/snow chances don`t exceed 10 percent. Monday is the warmest day with highs around 10 degrees above normal except across lowest elevations where the inversion will hold highs near normal. This can be seen in Monday`s forecast high of 55 degrees for both Ontario and McCall. LONG TERM...Tuesday through Saturday...The development of a deep upper trough off the West coast will rebuild a ridge over the region Tue/Wed. This will be dirtier ridge, bringing more extensive high cloud cover than what we see this weekend. There remains good agreement in the 00Z models to bring the trough onto the coast late in the week kicking off a period of more active weather heading into mid-November. Precipitation chances increase from west-east on Thursday with the entire region covered in 30%+ probabilities Thursday night through Saturday. Snow levels will start out above 8kft MSL on Thursday, dropping to 5-6kft by Saturday as the first trough passes. Temperatures hold around 10 degrees above normal (lowest elevations excluded) through Thursday, with the flip to a trough cooling temperatures to around normal starting Friday. && .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...JDS AVIATION.....CH AIR STAGNATION...DG/JDS SHORT TERM.......DG LONG TERM........DG