Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 252237

Area Forecast Discussion
National Weather Service Sacramento CA
337 PM PDT Wed Apr 25 2018

Mainly dry and warm this week except for a chance of a few
afternoon showers or thunderstorms near the Sierra Crest. Cooler
weather Friday into the weekend with increasing chances for
mountain showers and thunderstorms.


Clear skies have continued through the day, with unseasonably mild
temperatures. Delta breeze influenced areas started several
degrees cooler, and are still generally a little less warm. The
Delta breeze should strengthen again tonight, bringing cooler
temperatures through the Delta into the southern Sacramento and
northern San Joaquin valleys. Highs on Thursday may well remain in
the 70s for those ares, low 80s elsewhere in the Valley.

The inversion cap has been limiting convective development over
the Sierra so far today. Have left just a slight chance for
isolated thunderstorms for the Sierra crest south of Highway 50
early this evening, but even this is looking unlikely.

Upper level ridging will remain over the area into early Thursday
as an offshore low slowly approaches, moving inland late Friday
into Saturday. Temperatures will cool further on Friday, to
around average, dropping below average on Saturday. Chances for
mainly mountain showers and thunderstorms will increase Thursday
afternoon and evening over the Sierra. Friday could see showers
into the northern Sacramento Valley, and showers and thunderstorms
over the mountains, becoming more widespread Saturday. EK


Extended models keep upper low over the Pacific Northwest and
Norcal as the prominent weather feature on Sunday. Models show
the best instability generally north of Highway 50 on Sunday, so
have shifted afternoon thunderstorm chances accordingly. A cool
airmass will keep temperatures a few degrees below normal on
Sunday. Shower threat over the mountains continues through
Tuesday afternoon in the western most portion of the cyclonic flow
of the low. Drier conditions and warmer temperatures expected by
the middle of next week as upper ridging from the eastern Pacific
extends into NorCal. Temperatures by the end of the forecast
period will be up to 10 degrees above normal for early May.



VFR conditions at the TAF sites the next 24 hours. Winds
generally 10 kts or less.


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