Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
009 FXUS65 KBOI 050439 AFDBOI Area Forecast Discussion National Weather Service Boise ID 939 PM MST Tue Feb 4 2025 .DISCUSSION...A cold front is tracking across eastern OR this evening, with snow showers along the front and snow covered roads in eastern OR. This front will slowly move eastward overnight and through southwest Idaho by Wednesday morning. Snow levels fall to 2000-3000 feet by Wednesday morning as the precipitation ends. Due to the strong winds aloft and along the front. Precipitation will mainly be focused on the mountains in Idaho, with the Snake Basin, including the Treasure and Magic Valley, seeing minimal amounts of precipitation. After a lull in precipitation, a storm system will bring snow to the region on Friday, with light snow accumulations across the area. Current forecast on track with no updates planned. && .AVIATION...Areas of MVFR to LIFR in valley rain/mountain snow and patchy fog. Mountains obscured. Precipitation moving from W to E tonight with cold front, tapering off Wed. Snow levels: 4500-6500 ft MSL lowering to valley floors by later Wed morning. Surface winds: SW-SE 10-20 kt, gusts 25-40 kt this afternoon/eve. Areas of low- level wind shear. Winds aloft at 10kft MSL: SW 40-60 kt. KBOI...Low VFR/MVFR in periods of light rain tonight. Brief transition to rain/snow mix with cold front around Wed/10Z as precip tapers off. Surface winds: variable around 6 kt, becoming SE 10-20 kt with gusts around 25 kt around 04Z, then becoming NW 5-15 kt with gusts to 20-30 kt with cold front Wed morning around 10Z. && .PREV DISCUSSION... SHORT TERM...Tonight through Thursday night...The stalled cold front remains just northwest of the forecast area this afternoon, sustaining scattered showers across much of the region. Surface observations and COOP station reports indicate snow levels around 5,000 feet in the West Central Mountains of Idaho, dropping to approximately 3,800 feet from Burns to Baker City. McCall has recorded about an inch of wet snow as of 1 PM. With snow levels already near valley floors in these areas, precipitation is expected to remain as snow overnight as the cold front moves through. Elsewhere, much of the region remains in the warm sector through late tonight, keeping valleys drier and warmer. Temperatures in parts of the Treasure Valley, Western Magic Valley, and along the Nevada border have already reached 50F. Strong winds aloft (40-60 kt at ~10,000 feet MSL) will continue to enhance downsloping in the Treasure Valley, limiting precipitation to the frontal passage. Some high-resolution guidance (about 20% of models) suggests little to no additional precipitation in this area. The cold front and associated upper trough will progress southeastward late tonight, lowering snow levels and cutting off precipitation. The front is forecast to reach Burns and Baker City around 9 PM MST, Boise around 5 AM MST on Wednesday, and the Western Magic Valley by 8 AM MST. While lower elevations of Baker and northern Harney counties, along with the West Central Idaho Mountains, have struggled to accumulate snow today, the falling snow levels could allow for brief but rapid accumulation before precipitation ends. The current winter weather advisory remains in place. Valley temperatures will remain above freezing overnight, so precipitation in these areas will fall as rain. A few snow showers may develop Wednesday afternoon and evening, primarily over higher terrain, as colder air moves in behind the departing trough. A brief dry period is expected Thursday before the next potential storm system arrives Thursday night into Friday. Forecast confidence remains low, similar to the previous Sunday/Monday system, due to significant variability in the ensemble/deterministic solutions regarding the placement of precipitation with the warm front. Depending on how the snow band ultimately sets up, this system could bring significant snowfall to portions of the forecast area. A majority of the latest guidance (about 75%) indicates impactful snowfall beginning Friday morning, which is reflected broadly in the new forecast. LONG TERM...Friday through Tuesday...A trough will progress southward along the west coast, pulling additional Pacific moisture into east Oregon and southwest Idaho on Friday. The colder air associated with the trough will keep snow levels at/near valley floors and increase the potential for widespread snow accumulations. Currently, the chance for precipitation remains relatively high (65- 85%) Friday morning, before drier air and gusty winds arrive from the northwest by Friday afternoon/evening. Max temperatures will lower approximately 5 degrees from Friday to Saturday with the passage of the trough. Lingering snow showers are possible over the weekend, with the best chance (20%) over west-central Idaho. Thereafter, models diverge early next week, with some ensemble members introducing another trough and snow showers across the area. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory until 5 AM MST Wednesday IDZ011. OR...Winter Weather Advisory until 4 AM PST Wednesday ORZ061-062. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...KA AVIATION.....SP SHORT TERM...JDS LONG TERM....SH