AGUS76 KRSA 241548 HMDRSA Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 830 AM PDT Wed Apr 24 2024 ...COOL WITH PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS POSSIBLE, ESPECIALLY OVER THE HIGHER TERRAIN THROUGH FRIDAY THEN WARMER AND GENERALLY DRY OVER THE WEEKEND INTO MONDAY... .METEOROLOGICAL CONDITIONS (WED AM - TUE AM)... Upper level low off the Srn CA coast this morning weakens as it approaches and moves onshore as a shortwave trough into Srn CA this afternoon into tonight. Isolated to scattered showers and isolated thunderstorms possible over the higher terrain of Nrn CA and over the Central Sierra and into Nrn and Central NV. Showers possible over Srn CA mtns this afternoon into Thursday morning. Low clouds over the CA coast with deeper marine layer for possible drizzle/ light rain this morning. Precip amounts generally 0.25 inches or less but local amounts to around 0.75 inches possible, especially over the Central Sierra into Central/NE NV. The shortwave trough moves to the east of the region Thursday morning as a shortwave trough and associated cold front move into the Pac NW and Nrn CA Thursday and trough deepens over the region Friday with additional waves of energy. This will bring precip mainly to the north, especially over the higher terrain on Thursday and spreading south on Friday. Precip amounts 0.5 inch to around an inch for the Smith Basin and west slope of Srn OR Cascades and Ruby mtns and generally a third of an inch or less elsewhere over the higher terrain in the north on Thursday. Precip amounts for Friday generally around a quarter of an inch or less except locally to around a half an inch in the Nrn Mtns including the Srn OR Cascades and Ruby Mtns and along the NW CA coast. Precipitation may stretch south along the Sierra and into Srn NV and possible a few showers over the transverse mtns and into San Diego Count Mtns Friday. The trough shifts to the east over the weekend with weak ridging over the region and a low pressure system approaching the B.C./ Pac NW coast. This will bring warmer and generally dry conditions to the region except some light precip possible over the far north, mainly over the NW CA coast and west slope of Srn OR Cascades over the weekend into Monday. Max temperatures near normal to 15 degrees below normal over most of CA and near normal to 10 degrees above normal for Srn OR and NV this afternoon cool to around near normal to 15 degrees below normal across the region by Thursday afternoon and similar Friday afternoon. Temperatures warm up to near normal for most of the region except around 10 degrees below normal along NW CA coast Sunday afternoon and warming to near normal to 10 degrees above normal over SE CA and most of NV on Monday. Overnight temperatures near normal to around 15 degrees above normal decrease to around normal Friday night then warming to near normal to 15 degrees above normal Sunday night. Freezing levels around 10000 ft and higher today then dropping to around 8000-10000 ft for CA on Wednesday and around 10000-11000 ft over NV then drop to around 5000-7000 ft over Nrn CA and 8000-10000 ft for Central and Srn CA and NV Thursday morning and around 4000- 6000 ft over Nrn CA and 6000-8000 ft elsewhere Friday night and rising to around 6000-8000ft over Nrn CA and 8000 ft and higher elsewhere over the weekend and 4000-6000ft over NW CA coast and Srn OR and 7000 ft and higher for the rest of the region on Monday. QPF graphics are available at www.cnrfc.noaa.gov/qpf.php Osborne $$