Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
552 FXUS65 KBOI 310230 AFDBOI Area Forecast Discussion National Weather Service Boise ID 830 PM MDT Thu May 30 2024 .DISCUSSION...Skies were mostly clear this evening except across NE Harney and NW Malheur counties due to smoke from a wildfire west of Van, Oregon. Winds will drop off by midnight, as they typically do. A small update will be done to add smoke to the grids where satelite imagery show it has the most impact. && .AVIATION...VFR. Mostly clear, except areas of smoke aloft N through NE of KBNO. Surface winds: W-NW 5-10 kt after 03Z. Winds aloft at 10k ft MSL: W-NW 15-25 kt. KBOI...VFR. Northwest winds through sunset, then light and variable, becoming NW 5-10 kt after 31/18Z. Weekend Outlook...VFR through Sunday. Increased clouds and a slight chance of showers and thunderstorms in the w-central Idaho mtns, north and east of KMYL on Saturday. Clouds increase late Sunday with chance of showers across e-central Oregon in the evening. Winds less than 10 kt on Friday, becoming W-NW 5-15 kt with local gusts to 25 kt Saturday and Sunday. && .PREV DISCUSSION... SHORT TERM...Tonight through Saturday night...Little change from previous forecasts. Clear and cool tonight, then sunny and 8-10 degrees warmer Friday as a Pacific upper ridge comes inland. Increasing clouds from the west Saturday as a weak Pacific trough comes inland, but even with clouds Saturday should be 5 degrees warmer than Friday under southwesterly flow aloft. The incoming Pacific trough will bring a 20-40% chance of showers to eastern Valley County/ID Saturday evening, and also a 10-20% chance of thunderstorms, but the rest of our CWA should stay dry and mostly cloudy as a weak cold front moves through. The clouds will keep low temps mild Saturday night. Winds will be light, except for westerly gusts 15-25 mph Saturday afternoon/evening in southeastern Oregon as the cold front moves through. LONG TERM...Sunday through Thursday...A transiting upper ridge will bring dry and warm weather to the region on Sunday, with clouds increasing late in the day. Precipitation spreads into SE Oregon and w-central Idaho Sunday night as an upper low approaches the Pac NW coast. Models remain in good agreement on the track and general timing as the low and accompanying cold front move through the region on Monday. This system is attached to a deep sub-tropical moisture tap that will push precipitable water values into the 95th percentile (around 1.00" across lower elevations). The current forecast track places the potential for heavier precipitation over the w-central Idaho mountains, where there`s a 20-30% probability of an inch or more of rainfall on Monday. Snow levels for much of this event will be at or above 10kft MSL, falling to around 8kft MSL Monday night as the precipitation ends. Thus expect to lose a good amount of remaining high level snowpack. What doesn`t come off with the rain on Monday will face building heat as an upper ridge quickly amplifies over the western US. High temperatures will push well above normal by Wednesday with lower valleys likely into the 90s by Thursday (about 15 degrees above normal). Lower portions of the Snake Plain are still looking at a 10-15% chance of hitting 100 by Thursday. && .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 DISCUSSION...SP AVIATION.....SP SHORT TERM...LC LONG TERM....DG