Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
409 FXUS65 KBOI 270404 AFDBOI Area Forecast Discussion National Weather Service Boise ID 904 PM MST Wed Nov 26 2025 .DISCUSSION...Light warm-frontal precipitation continues across NE Oregon and SW Idaho along and north of the Snake Plain this evening. Snow levels have risen above most mountain valleys, currently at 6000-8000 feet MSL. This moisture will eventually exit toward the northeast tonight, paving the way for patchy valley fog and/or low cloud decks to form and linger through Thursday morning. Models currently have the highest chance of fog in the Lower Treasure Valley during the morning hours. The forecast area will then reside in the warm sector of the incoming trough Thursday, supporting relatively mild daytime temperatures. Meanwhile, an upper level front will progress from west to east through the region and promote dense cloud cover for much of the day. A slight chance of light precipitation remains in the forecast for NE Oregon and W-central Idaho Thursday afternoon. Surface cold front still expected Friday morning. See previous discussion for more details. && .AVIATION...Areas of MVFR/IFR due to low ceilings and light precipitation obscuring mountains will continue until around 06Z-07Z generally north of a KBKE-KONO-KSUN line. Decreasing precipitation and improving ceilings after midnight. VFR prevailing along and south of that line. Reductions in visibility due to fog (20-40% chance) around KMYL, KBKE, KONO, and KEUL are possible from 10Z to around 16Z tomorrow morning. Expect mostly VFR conditions on Thursday across SW Idaho and SE Oregon. Surface winds: variable 10 kt or less, becoming E to SE at 10-15 kts across the Snake River plain on Thursday. Winds aloft at 10kft MSL: W 20-30 kt. KBOI...VFR with light and variable winds overnight. Showers in the vicinity until about 05Z. A 10% chance of IFR/LIFR fog moving within 5 miles of terminal Thursday AM. Otherwise, dry weather expected on Thursday with surface winds becoming southeasterly at 5 to 10 kts. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night...An upper level low in the north Pacific and its associated fronts are driving much of the weather in the short term. Tonight through Thursday morning, a warm front will be moving northeastward out of our area. Precipitation chances along and behind the front are 40-60%, located mostly in SW-central Idaho and NE Oregon high terrain. As the warm front has moved through most of the area already, snow levels are rising up to 6-8 kft MSL in the warmer airmass. This will prevent much of the area from seeing further snow accumulation, but ridges in the West Central and Boise Mtns could see light accumulation. Otherwise, up to 0.1 inches of rainfall will fall in that same area. While there were no obs of freezing rain this morning, thermal profiles in the West Central Mtns are riding the line again tonight. However, the surface may be just too warm and air loft be just to cold to refreeze any melted precipitation so the chance remains less than 10%. Precipitation follows the front northeastward out of the area Thursday morning. The warmer airmass sticks around for almost all of Thanksgiving day, with slightly drier air aloft limiting precipitation to the region just north of our CWA. Temperatures will return to the 5-10 degrees above normal we`ve seen for much of November, and winds increase in SE Oregon and ridgetops ahead of Friday. The cold front portion of the upper low moves in Thursday night and Friday morning bringing more precipitation and dropping temperatures. The high terrain in NE Oregon and W-Central Idaho continue to be the favored areas for precipitation, with chances 40-60% increasing to the north. A 15% chance of precipitation extends as far south as the Owyhees and Rome, Oregon. The most likely timing of precipitation is Friday morning through midnight Friday night. The colder airmass will drop snow levels from 5-6 kft MSL that morning to 3-4 kft MSL at midnight. Mountain towns and passes could see up to 1 inch of snow, while ridges see up to 3 inches. Rainfall/liquid equivalent in the same area is forecast to be up to 0.2 inches. Behind the front, temperatures will drop to a few degrees above normal, and gusts up to 35 mph are possible in Central Idaho open areas and ridges. LONG TERM...Saturday through Wednesday...The jet stream will flow up and over an upper level ridge positioned off of the west coast and then down and around a broad upper level trough over the continental U.S. This pattern will have enough of a northerly component in our area to cool temperatures down to seasonal normals for this time of year. A shortwave trough embedded in the jet stream will ride over the top of the ridge and into the Pacific Northwest on Saturday night and Sunday bringing a 20 to 30 percent chance of precipitation to much of southwestern Idaho and southeastern Oregon. It looks dry behind that shortwave on Monday, but another shortwave will approach the area on Tuesday and Wednesday increasing the chance of precipitation again. Snow levels are expected to generally remain at or above 4000 feet, so any snow accumulations should be limited to the mountains. && .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...SH AVIATION.....TL SHORT TERM...JM LONG TERM....JB