Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
552 FXUS65 KBOI 170951 AFDBOI Area Forecast Discussion National Weather Service Boise ID 351 AM MDT Tue Sep 17 2024 .SHORT TERM...Today through Thursday night...Showers and thunderstorms continue to rotate around a closed upper low centered over southwest Idaho this morning. The low will gradually lift to the northeast today with wrap-around shower and thunderstorm development keeping at least a 60% chance of precipitation in the forecast across most sites through this afternoon. Showers and thunderstorms today will bring locally heavy rainfall which will continue to pose a threat for flooding and debris flows on recent burn scars. Storm motion and speed will vary as individual cells follow the upper low circulation. This could lead to slower movement and training of storms near the upper low center over SW Idaho. Shower and thunderstorm coverage will diminish this evening as the low exits into MT, but wraparound moisture and instability will keep a low chance of showers in the w-central Idaho mountains through Wednesday. A second low dropping down the coast will track further west and south than the current system. This will allow much of the region to dry out while areas near the northern NV border keep a 20-30% chance of showers through Thursday. Today is the coolest day of the week with high temperatures about 15 degrees below normal. Wednesday and Thursday will warm about 5 degrees each day bringing lower elevations back into the mid-70s by Thursday. .LONG TERM...Friday through Tuesday...Widespread model agreement amongst deterministic solutions exists in the position of an upper level low pressure system on Friday. This will continue to bring below normal temperatures and a slight chance of showers to the region through Sunday morning. Northwest flow will then return as the low center moves East on Sunday. Temperatures will climb slightly and conditions will be mostly dry. The GFS/ECMWF runs then hint at a shortwave trough moving through northern and eastern Idaho, which would bring another chance of precipitation to the Central ID Mountains on Monday night into Tuesday. A weak ridge will then likely build in according to ensemble clusters, bringing a return to normal temperatures and dry conditions for Tuesday. && .AVIATION...Mostly VFR. Areas of MVFR in showers and isolated thunderstorms, mainly in southwest Idaho after 17/21Z. Gusts up to 40 kt with the stronger storms. Surface winds: W-NW 5-10 kt gusts to 25 kt in SE Oregon, becoming generally variable 5-10 kt overnight. Winds at 10kft: NE 10-20 kt becoming W-NW 20-30 kt after 18/00Z. KBOI...VFR. A 90 percent chance of showers this morning, becoming 30 percent by early afternoon. A 20 percent chance of thunderstorms after 18/23Z, accompanied by wind gusts up to 40 kt. Surface winds: variable overnight, becoming mainly NW 4-8 kt. && .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...DG LONG TERM....SA AVIATION.....SA