Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
853 FXUS65 KBOI 012042 AFDBOI Area Forecast Discussion National Weather Service Boise ID 242 PM MDT Sat Jun 1 2024 .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. && .AVIATION...VFR with mid and high level clouds spreading across the area late this afternoon and evening. A slight chance of showers until about 02/06Z, but low confidence (less than 20 percent) in any of the showers reaching terminals. Slight chance (less than 20 percent) of thunderstorms in the West Central Mountains (including KMYL). Gusts up to 30 kt near showers and thunderstorms. Surface winds: W-NW 5-15 kt. 10k ft MSL winds: W 10-20 kt. KBOI...VFR. NW winds 10 kt or less. Low confidence (less than 20 percent) of a shower after 02/00Z. Sunday Outlook...VFR through Sunday afternoon with showers developing in KBKE area. High confidence of MVFR conditions developing across the north (KBKE-KMYL) associated with widespread rain Sunday night. SW-NW winds 5-15 kt with local gusts to 25 kt. && .HYDROLOGY...We`re watching the northern mountains as an atmospheric river will bring widespread rain Sunday night and Monday. Widespread rainfall totals of 1.00 to 1.50 inches with locally higher amounts are expected in these areas. Rain combined with high elevation snowmelt will result in rising water levels in rivers, creeks, and streams. Mainstem rivers currently are not forecast to reach flood stage but some smaller tributary creeks and streams could reach or exceed bankfull resulting in minor flooding. Mud and rock slides could be an issue in steep terrain as well. There is a Hydrologic Outlook in effect providing details as well. && .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...JM LONG TERM....TL AVIATION.....TL HYDROLOGY....TL