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Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
525 FXUS65 KBOI 201536 AFDBOI Area Forecast Discussion National Weather Service Boise ID 936 AM MDT Sat Jul 20 2024 .DISCUSSION...Continued smoky and very hot with upper level ridge extending from the Great Basin northward through the Intermountain region and into Alberta. High confidence that heat will continue through next Thursday, but there is growing confidence in a cooling trend beginning Friday. Pacific short wave trough currently forecast to move northward along the NW coast Sunday will set off scattered thunderstorms in eastern Oregon Sunday afternoon, maximizing Sunday evening. Current forecast already has this but PoPs may be increased in the afternoon package. On Monday thunderstorms will be mainly near the Nevada border and along the eastern edges of Valley and Elmore Counties in Idaho. Current forecast is on track. && .AVIATION...MVFR or low VFR in smoke. Local IFR northwest of KONO. High density altitude from heat. Isolated afternoon thunderstorms near the NV border and in the central ID mountains. 30-40 kt outflow winds from thunderstorms. Surface winds: NW- NE 5-15 kt. Gusts 15-25 kt near KBKE KONO this evening. Winds aloft at 10kft MSL: variable 5-15 kt. KBOI...MVFR or low VFR visibility due to smoke. High density altitude from heat. Surface winds: Light/variable until noon, then NW 8-10 kt until sunset, then S-SE 5-10 kt overnight. Sunday Outlook...MVFR or low VFR to local IFR from smoke. High density altitude from heat. Scattered thunderstorms Sunday in southeast OR, especially in Harney County, with 35-45 kt erratic outflow winds. Surface winds: E-SE 5-15 kt. && .PREV DISCUSSION... SHORT TERM...Today through Monday night...Upper level ridge will continue to expand over the area today, with a few degrees of warming compared to Friday. Record high temperatures over the short term in some locations, depending on how thick the smoke is. Wildfire smoke continues to impact the area, limiting temperatures a few degrees below previous forecasts. We used bias corrected temperatures over the past 10 days to account for wildfire smoke in the temperature forecasts in the short term. The hot conditions will support unstable conditions, with isolated thunderstorms over central ID mountains and along ID/NV border this afternoon. A shortwave off the CA coast will support increased chances of thunderstorms on Sunday afternoon, especially across eastern OR as the system moves north along the WA/OR coast. A slight chance of thunderstorms continues into Monday afternoon as this system slowly tracks northeastward. Thunderstorm threats will mainly be erratic outflow wind gusts up to 50 mph and lightning. Excessive heat warnings, and heat advisories, remain in effect. LONG TERM...Tuesday through Saturday...The upper level ridge will continue through at least Thursday with continued hot conditions. The ridge will also have substantial moisture in it with precipitable water values in the 70-80th percentile for this time of year. This will keep a threat of thunderstorms each afternoon through Thursday, mainly over the higher terrain. A trough over southwest Canada will bring cooler temperatures by next Friday and Saturday, with temperatures cooling to near normal or a few degrees below. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Excessive Heat Warning until 9 PM MDT Wednesday IDZ012-014-033. Heat Advisory until 9 PM MDT Wednesday IDZ015-016-029-030. OR...Excessive Heat Warning until 9 PM MDT /8 PM PDT/ Wednesday ORZ063-064. Heat Advisory until 8 PM PDT Wednesday ORZ061-062. Red Flag Warning from noon MDT /11 AM PDT/ Sunday to midnight MDT /11 PM PDT/ Sunday night ORZ636-637. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...LC AVIATION.....LC SHORT TERM...KA LONG TERM....KA