246 FXUS65 KBOI 231656 AFDBOI Area Forecast Discussion National Weather Service Boise ID 956 AM MST Sun Feb 23 2020 .DISCUSSION...Clouds are spreading into the region from the northwest this morning, ahead of an upper level system that will drive a cold front through the region later today. Latest estimate is that the front will enter Baker County and southeast Oregon mid-afternoon, get into southwest Idaho late afternoon and early evening, and exit the western Magic Valley before midnight. Still expecting 1 to 3 inches of snow above around 5000 feet, with just a few hundredths of rain in the lower elevations. There is some instability with this system, and a few showers could become strong this afternoon along and just behind the front. These isolated showers could produce up to a tenth of an inch of rain, possibly mixed with graupel, but coverage will be minimal. No changes to the forecast at this time. && .AVIATION...VFR this morning. Areas of MVFR and local IFR with mountain obscuration associated with a cold front crossing the region this afternoon. Showers this afternoon across Baker County Oregon and the Central Idaho mountains with snow levels 3000-4000 ft MSL. Scattered showers spreading south across SW Idaho following the front this evening, with snow levels 3500-4500 ft MSL. Most showers across SW Idaho ending by 24/06z, with showers and mountain obscuration continuing over the West Central mountains overnight. Surface winds: generally SE 5-15 kts, becoming W to NW 10-20 kts behind the cold front with gusts up to 35 kts. Winds aloft at 10k feet MSL: W 35-55 kts, becoming NW after 24/06z. && .PREV DISCUSSION... SHORT TERM...Today through Tuesday night...Upper level trough and associated cold front reaching the Pacific Northwest coast this morning will quickly move east reaching the forecast area later this afternoon. Convective showers will follow frontal passage with snow levels initially around 4000 to 5000 feet, accumulating snow will be confined to the mountains and higher foothills. Amounts will be generally light, with 1 to 3 inches expected. Rainfall in lower elevations will be 0.05 inches or less. Stronger showers could produce a brief period of graupel. Winds along and behind the front will be generally from the northwest 10 to 20 mph with gusts to 30 mph. Even higher gusts are likely in southeast Oregon, with gusts above 40 mph. Colder but dry conditions follow the front as a ridge begins to push east over the region. Temperatures will be just above normal today falling about 4 degrees below normal for Monday. LONG TERM...Wednesday through Sunday...An upper ridge will build into the region through Friday, resulting in dry conditions and a warming trend with temperatures 5-10 degrees above normal by Friday. Southwest flow aloft will become increasingly moist through the weekend as the next upper trough enters the Pacific Northwest. Shower chances will favor the higher elevations on Saturday with a chance for all areas Saturday night through Sunday. Snow levels are expected to remain above lower valley floors. Temperatures will remain above normal, with slight cooling on Sunday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...SP AVIATION.....AL PREV SHORT TERM...JDS PREV LONG TERM....BW |