Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
097 FXUS66 KSTO 170915 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 215 AM PDT Wed Jul 17 2024 .SYNOPSIS... Seasonably hot weather the next couple of days, then hotter weather returns over the weekend into next week && .Key Points... - Warming trend by the weekend with areas of Major to Extreme HeatRisk returning early next week. - Slight chance for late-day thunderstorms over the Sierra south of Lake Tahoe beginning Thursday, spreading north over the Sierra/Cascade crest during the weekend. && .Discussion... A band of high clouds is moving east across far northern California associated with the upper low moving northward along the southwest Oregon coast, otherwise skies are clear across interior NorCal as the elevated monsoon moisture has finally shifted to the north and east of the region. IR difference imagery shows the marine layer entrenched along the coast with profiler data indicating its depth around 2-3k ft. Onshore flow continues with local southerly gusts of 15-20 mph continuing in the Sacramento Valley. This has brought cooling along with a little higher humidity to much of the area. Minor height rises aloft develop as the low lifts further north into the PacNW leading to diminishing onshore flow today. This will result in slightly warmer temperatures in the Delta Breeze influenced areas and little change elsewhere. A gradual warmup begins Thursday and continues into the weekend as the southwest high builds back to the northwest toward NorCal bringing a return of triple digit heat through most of the Central Valley. Elevated moisture working its way around the periphery of the high will bring a return of late-day thunderstorm chances to the Sierra south of Lake Tahoe beginning Thursday with the potential for storms to spread north along the Sierra/Cascade crest by the weekend. && .EXTENDED DISCUSSION (Sunday THROUGH Wednesday)... Another bout of heat is looking likely for the region early next week as the southwest high shifts westward closer to NorCal. At this point it`s not looking to be as extreme (either in magnitude or duration) as the heatwave earlier this month. With valley highs returning to the 105-110 range beginning Sunday, areas of Major to Extreme HeatRisk will once again be possible for the Central Valley and foothill thermal belts. Elevated moisture/instability is also forecast to return with the heat with thunderstorm chances potentially spreading into the northern mountains by Monday. && .AVIATION... VFR conditions next 24 hrs. Surface wind gusts generally under 12 kts except local southwest gusts 15-25 kts vicinity west Delta. && .STO WATCHES/WARNINGS/ADVISORIES...None. && $$