Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
308 FXUS65 KBOI 090231 AFDBOI Area Forecast Discussion National Weather Service Boise ID 831 PM MDT Wed Oct 8 2025 .DISCUSSION...No changes to the forecast. Thursday and Friday will be about 10 degrees above normal, with highs in the Snake Plain near to above 80 degrees. The upper low off the PacNW coast is strongly pulling warm and dry air out of the south- southwest. This same system is still on track to move inland Friday, bringing isolated showers and storms that afternoon and evening. The cold front passes Friday night, keeping winds gusty and dropping temps to 5 degrees below normal Saturday. Showers and unsettled weather continues through next week, with snow above 5-6 kft MSL. && AVIATION...VFR. LLWS in the Snake Plain and valleys as strong winds above the surface flow across diurnal down-valley winds. Surface winds: E-SE 5-15 kt Winds aloft at 10kft MSL: S 15-25 kt. KBOI...VFR. LLWS possible overnight and tomorrow morning. Surface winds: SE 10-15 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night...Unseasonably warm and dry conditions will dominate through the first half of Friday, with highs running 10 to 12 degrees above normal and peaking in the low 80s on Thursday. This warming trend is fueled by strong southwesterly flow aloft as an upper- level trough gradually moves south along the Pacific Northwest coast. As the system deepens into a closed low off the Oregon coast, a dry slot will form over southeast Oregon and southwest Idaho for much of Friday. While this dry influence keeps early fall-like conditions in place, instability along the edge of the moisturedrawn from the southwestern U.S.will allow for a slight chance of thunderstorms (1020%) across south-central Idaho during the Friday afternoon and evening hours. The greater coverage of precipitation begins late Friday evening with the arrival of the cold front. The chance of showers will increase to 2040 percent in the valleys. However, pronounced southwest flow behind the front will favor upslope regions, with the west-central Idaho and Boise Mountains expected to receive the brunt of the moisture, where shower chances climb to 6080 percent. LONG TERM...Saturday through Wednesday... Unsettled conditions will prevail throughout the long term. Deterministic and ensemble models are in good agreement of the closed-low off the coast of California coming onshore Saturday. Steering flow from the trough should keep the remnant moisture from what is now Hurricane Priscilla and Tropical Storm Octave to our south and east. None the less, this trough will bring with it cooler temperatures and showers across our area. Chances of precipitation Saturday into Sunday morning will be 60-80% across higher terrain and 40% in valley locations. Precipitation chances lower slightly Sunday afternoon into early Monday, as brief shortwave ridging builds in. Model ensembles are coming into agreement on a reinforcing shot of energy propagating through the northwest flow aloft and closing off into a low just west of our area. As a result, precipitation chances will remain elevated Monday through Wednesday. Both the GFS and Euro ensembles have been consistent showing measurable precipitation throughout the long-term, a sign of the unsettled conditions to come. The precipitation won`t just be in the form of rain throughout the long term. Snow levels will lower to 5-6kft by Saturday night/Sunday morning before hovering around 6-7kft beyond Sunday. This will allow snow to fall over higher terrain. Any accumulations won`t stick around for too long as our area gets into the warm sector of the second system, warming daytime highs to above freezing. Temperatures will be cool to around 10 degrees below normal by Sunday, following a cold frontal passage from the first system, generally hovering there through Wednesday. Although there will be a brief period of warming Monday as we get into the warm sector of the second system. && .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...JM AVIATION.....JM SHORT TERM...JDS LONG TERM....NF