Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
221 FXUS65 KBOI 030358 AFDBOI Area Forecast Discussion National Weather Service Boise ID 858 PM MST Tue Dec 2 2025 .DISCUSSION...Light showers associated with a convergence zone in the Magic Valley will persist through this evening. While ITD web cameras showed light snow near Hazelton, ID, nothing has been reported further west at Jerome or Twin Falls as of 8 PM MST. Elsewhere, skies are clearing as the system exits the region. West to northwest winds continue, though speeds have decreased compared to earlier this afternoon. For Wednesday morning, some high-resolution guidance continues to suggest stratus and fog development in the Snake River Plain, extending from the western Magic Valley through the Upper Treasure Valley. However, there is considerable skepticism regarding this extent, especially for fog, given the persistent westerly winds and lack of additional surface moisture today. The last three runs of the HRRR and the RRFS have backed off on fog and stratus in the Treasure Valley, limiting the extent to the northern parts of the western Magic Valley (including Jerome) and along the foothills of the Central Idaho Mountains north of Mountain Home. This scenario appears far more likely given the current precipitation footprint and low ceilings. Consequently, there is high confidence (80% chance) in stratus and fog across the western Magic Valley, which could impact the Wednesday morning commute. Conversely, there is low confidence (30% chance) in development further west across the Treasure Valley. The current forecast reflects this reasoning well, so no updates are needed at this time. && .AVIATION...Snow showers and low ceilings near the Magic Valley resulting in MVFR/IFR conditions. Showers ending around Wed/06z. Patchy fog/low stratus developing after Wed/06z Resulting in IFR/LIFR conditions, highest confidence in the Magic Valley near KJER. Surface winds: W-NW 5-15, becoming variable up to 13 kt overnight. Winds aloft at 10kft MSL: N-NW 15-30 kt. KBOI...Mainly VFR. Fog/Low stratus possible resulting in IFR/LIFR conditions (30% chance) early Wednesday morning. Confidence on fog/low stratus development is low. Surface winds: NW 8-12 kt, becoming light and variable after Wed/12z. && .PREV DISCUSSION... SHORT TERM...Tonight through Thursday night...A cold front and upper level trough continues to move southeast today, with lingering rain and snow showers over the area. Showers will taper off after sunset. The system will bring areas of low clouds and fog to the area tonight and on Wednesday as upper level ridging builds in behind the cold front. The ridge will remain over the area through Thursday before the next system arrives from the northwest. Snow is expected over the west central ID mountains and Blue Mountains Thursday afternoon and evening. Snow accumulations of 2-4 inches expected Thursday evening. LONG TERM...Friday through Tuesday...An active pattern is forecasted for this weekend. An upper-level ridge will further build into the Eastern Pacific, with moisture and upper-level shortwave disturbances moving through the area through the long term. PoPs will be active for much of the long term with these disturbances. Snow levels will rise from around 4000-6000 feet Friday morning (starting as snow in mountain valleys) to around 5500-7000 feet Friday night, and possibly as high as 8000 feet as the warm front passes through late in the day. Saturday and beyond, snow levels will fluctuate slightly with passing systems, but should average around 5000-7000 feet. Precipitation will let up on Monday as the upper-level ridge axis builds closer to the region, however precipitation looks to return Tuesday with another upper-level shortwave passage. Temperatures Friday through Tuesday should average around 10 degrees above normal, and passing systems will bring breezy conditions. && .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.....NF SHORT TERM...KA LONG TERM....CH