FXUS65 KBOI 101636 AFDBOI Area Forecast Discussion National Weather Service Boise ID 936 AM MST Mon Feb 10 2025 .DISCUSSION...This morning was much colder than yesterday in Idaho (except in the Magic Valley), and slightly colder than yesterday in eastern Oregon. Latest guidance still has the coldest weather slated for Wednesday morning, and even colder than previous forecasts. Before getting that cold, however, an upper trough and reinforcing arctic front will pass through from north to south tonight. After that arctic air will come in under northerly flow aloft straight from the north pole. That flow will carry a 1045 mb surface high southward from BC into WA and OR and western ID. Previous forecasts were slightly milder Tuesday morning with the upper trough and frontal clouds moving through, but now it looks like the trough and front will arrive earlier so that Tuesday morning can become colder. Current Cold Weather Advisory for eastern OR will be expanded into western ID, certainly for Tuesday night/Wednesday morning, and possibly Tuesday morning as well. Moist and warmer westerly flow aloft will replace the arctic northerly flow beginning Thursday, with most models showing a light to moderate snowfall in our CWA Thursday and Friday. With the surface being so cold, any snow that falls will cover the roads and create travel impacts. More on that in the afternoon package. && .AVIATION...MVFR-IFR low stratus or dense fog will continue at several TAF sites through late this morning. Dense Fog will continue for KONO and KBNO through 18z. Isolated snow showers and widespread mountain obscuration across the West Central Mountains today. Surface winds: variable up to 10 kt. Winds aloft at 10kft MSL: W-NW 10-20 kt. KBOI...VFR and light winds today. Stratus/fog possible Tuesday morning, with a 30% chance of occurrence. && .PREV DISCUSSION... SHORT TERM...Today through Wednesday night...Fairly dry northwest flow aloft will continue today and tonight, with very light snow possible in the mountains (10-20% chance). Flow becomes zonal tonight in advance of a weak upper level trough that will move through Tuesday. PoPs increase slightly Tuesday into Tue night, but moisture is limited with this system. Wed will be dry and cold. Temperatures will be much below normal through the short term period. A Cold Weather Advisory continues through Wed morning for southeast Oregon, while an Extreme Cold Warning continues for the Camas Prairie. Temps in Fairfield are expected to get below -20 both Tue and Wed mornings, while temps in SE Oregon will be in the low single digits Tue morning and below zero Wed morning. Fog and/or low stratus is possible Tue morning over much of the lower elevations, with dense fog possible (10% chance). However, low clouds are more likely. LONG TERM...Thursday through Monday...A strong upper level system will move into the area from the west Thursday and pass over the area Friday. Snow will fall at all elevations, with amounts ranging from 1 to 3 inches in the Treasure and western Magic Valleys, from 3 to 8 inches in northern Malheur and Harney counties, and from 1 to 4 inches in Baker County. The mountains should see relatively light snow, from 2 to 6 inches. After a relatively dry Saturday, another system is expected to move in Saturday night through Monday, spreading valley rain and mountain snow across the region. Snow totals in the mountains are forecast to be moderate. Temps through the long term are forecast to remain below normal, but be significantly warmer than what we will experience in the short term. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Extreme Cold Warning until 10 AM MST Thursday IDZ028. OR...Cold Weather Advisory until 10 AM MST /9 AM PST/ Thursday ORZ061>063. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...SP AVIATION.....JDS SHORT TERM...SP LONG TERM....SP