Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
445 FXUS65 KBOI 202054 AFDBOI Area Forecast Discussion National Weather Service Boise ID 254 PM MDT Mon May 20 2024 .SHORT TERM...Tonight through Wednesday night...An active and unsettled pattern is on deck for the short term period as successive upper level lows move through the region. The first upper level trough will continue to dig through the region today, bringing sufficient instability for thunderstorms and showers. As of 1:00pm MDT, there is one weak thunderstorms just north of Gooding, ID, bringing strong winds and brief rain. Winds are gusting quite a bit throughout the region with KBOI sustained at 18 mph with gusts to 33 mph. This is mainly due to downsloping and gradient winds, but additional outflows could strengthen local gusts to 40-50 mph. Radar indicates showers developing and satellite visible imagery shows widespread cumulus development throughout the region. Therefore, have increased chance of precipitation and coverage of showers and thunderstorms to further west over portions of southeast Oregon. Hi-res model guidance continues to show pulsing showers- thunderstorms over much of southwest Idaho through the early evening. Tuesday should be somewhat mild, with a weak upper level ridge building ahead of a much colder and wetter cut off low late Wednesday into Thursday. Winds will be mostly light, with Tuesday likely being the warmest day of the week. By Tuesday evening, valley rain and snow above 6000 feet should begin in southeast Oregon. Precipitation will come in a line with the initial cold frontal passage late Tuesday night. By early Wednesday morning, precipitation will spread into southwest Idaho. Most of this precipitation should be stratiform with the initial line on Wednesday morning, but convective showers with a stray thunderstorm could form over the Central ID mountains. Snow levels will be right around 6500 feet during the day, lowering to 5000 feet overnight. Therefore, light snow is possible early Wednesday and late Wednesday night. Temperatures will be below normal after Tuesday. LONG TERM...Thursday through Monday...Moisture wrapping around the exiting closed low will keep rain and snow over the mtns of Baker County and w-central Idaho Thursday. Liquid amounts will be less than a tenth of an inch (0.10) limiting additional snow totals to less than an inch. Snow level forecasts remain between 4500-5000 feet Thursday morning rising to 6-7kft MSL by afternoon. Otherwise most of SE Oregon and SW Idaho are dry on Thursday and the drying trend will extend into the mountains Thursday night as the low exits eastward. Friday will be mostly dry though the Baker County and w- central Idaho mtns will keep a 20% chance of light afternoon showers fueled by increasing instability and moisture ahead of the next cold- core low. Precipitation accompanying this next low will arrive Friday night, carrying through Saturday night as the it tracks from WA into eastern ID. Among the deterministic models the best overlap for precipitation remains across e-central Oregon and w-central Idaho where probability for rain/snow remains 30-60%. Areas from the I-84 corridor and points to the south and east will see lesser probabilities generally below 25%. Sunday and Monday will trend drier as a shortwave ridge moves into the area. Thursday will be the coolest day, warming closer to normal Friday through Sunday, warming above normal on Monday. && .AVIATION...Mainly VFR. Scattered showers and isolated thunderstorms will continue through this evening across SW Idaho and far E Oregon. Mountains obscured in showers. Thunderstorms capable of small hail and outflow gusts to 30-40 kt. Snow levels 5500-6500 ft MSL. Surface winds: W-NW 5-15 kt, becoming 10-20 kt with gusts to 25-30 kt this afternoon. Winds aloft at 10k ft MSL: N-NW 10-20 kt. KBOI...VFR. Showers in the vicinity, which could impact the terminal. Nearby shower and thunderstorm activity will be capable of producing outflow wind gusts 30-40 kt that could travel to KBOI. Best chance of showers and winds through Tue/01Z. W-NW winds becoming gusty by late morning. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...SA LONG TERM....DG AVIATION.....DG