Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
849 FXUS65 KBOI 020223 AFDBOI Area Forecast Discussion National Weather Service Boise ID 823 PM MDT Sat Jun 1 2024 .DISCUSSION...Showers continue this evening, but they are very light, and there appears to be more virga than precipitation reaching the ground. This will change drastically over the next 24 hours as the previously described atmospheric river brings moderate to heavy rain to the region. See the previous discussion below for details. The forecast is in good shape this evening and no update it planned at this time. && .AVIATION...VFR with mid and high level clouds. A slight chance of showers until about 02/06Z, but low confidence (less than 20 percent) in any of the showers reaching terminals. Gusts up to 30 kt near showers and virga. Surface winds: SW-NW 5-15 kt. 10k ft MSL winds: W 10-20 kt, becoming SW-W 15-25 kt by 02/18Z. KBOI...VFR. W to NW winds 10 kt or less. Continued nearby virga with occasional gusts to 15 kt through 02/04Z. && .PREV DISCUSSION... SHORT TERM...Tonight through Monday night...A weak trough is approaching today, bringing some mild unsettled conditions. Upper level clouds today are limiting shower development, but isolated showers and scattered virga is evident over the higher terrain this afternoon. There is still a 10-20% chance of thunder over the West Central Mountains this evening. The trough brings a weak cold front though this evening that will cause keep winds a little breezy overnight with gusts to 25 mph. The front will also bring cooler/drier air for early Sunday. An atmospheric river in the Pacific will transport up to 1" of PWat Sunday evening through Monday night. The enhanced moisture flow is supporting precipitation chances of 70-90% for most of the area, with chances of 90-100% over mountains. Rainfall totals in the West Central Mountains and Boise Mountains are around 1" in Valleys to 2" on ridges, with a few summits forecast to receive even more. The significant mountain rain, lows on Monday morning above freezing, and lingering snowpack are creating some concern for small stream flooding in the mountains. There is also some convective potential Monday afternoon that could see some terrain driven storms forming. This raises concern for rapid onset flooding, but convective potential may be limited in the cloud cover and steady rain. Even a little concern for convection on saturated soil and snowpack was enough to warrant an increase to slight risk in the WPC ERO. Overall, confidence in flood potential is a little too low for a Flood Watch at this time as river, but a Hydrologic Outlook has been issued. Elsewhere this event still looks like a soaker, with portions of eastern Oregon in a marginal risk for excessive rain. Storm total QPFs in the Snake Plain range from 0.2" along the southwestern edges and 0.5" along the northeastern edges and foothills. Winds will gust to 20-30 mph Sunday afternoon/evening ahead of the moisture. LONG TERM...Tuesday through Saturday...Zonal flow is forecast over the area Tuesday with dry conditions. Ensemble forecasts continue to show a strong upper level ridge developing over the region the second half of next week resulting in hot/mostly dry conditions. Temperatures will warm from around normal on Tuesday to 15-20 degrees above normal Thursday through Saturday. Models are showing increasing moisture in southerly flow aloft late next week resulting in a slight chance of showers (generally less than 20 percent) near the Nevada border Thursday afternoon. The chance of showers increases to 15-30 percent Friday and Saturday generally across the entire forecast area. && .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...JM LONG TERM....TL