Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 222235

Area Forecast Discussion
National Weather Service Sacramento CA
335 PM PDT Sat Jul 22 2017


Hot and dry weather this weekend with widespread triple digit heat
across the Valley. A little cooler with near normal temperatures
next week. A slight chance of afternoon mountain thunderstorms
Sunday into Tuesday.


A hot day today, with temperatures as high as 106 in Redding at 3
pm. Temperatures in the Valley are generally in the upper 90s,
with many locations reaching triple digits. High pressure over
the region will continue the heat into Sunday, maybe a few degrees
less hot than today as a weak upper low off the coast approaches.
The Heat Advisory continues into Sunday evening for the northern
Sacramento Valley and surrounding foothills.

The approaching upper low will bring sub-tropical air northward
up the Sierra crest by afternoon. Models show instability along
the crest bringing a slight chance of thunderstorms chance along
the Sierra crest northward into eastern Shasta County. The upper
low digs a bit farther southward on Monday. Southeast flow aloft
will continue to bring moisture and instability up the Sierra
crest so thunderstorm threat continues. More airmass cooling
should drop daytime highs most valley locations down to below the
century mark. Upper low remains centered around the north coast on
Tuesday bringing still more cooling. Daytime highs next Tuesday
are forecast to drop to near or even a little below normal. Upper
level southerly flow will continue to bring afternoon and evening
thunderstorm threat up the Sierra and Cascade crest.



Warm, dry weather expected for the extended period. Current
agreement among models weakens the upper level low and brings it
over NorCal on Wednesday. Thunderstorm potential shifts southeast
of the area and temperatures begin to slightly increase with the
northern Sacramento valley highs reaching the century mark again.
Dry weather expected through the weekend. Temperatures will
remain near seasonal normals through the week. High pressure
begins to build again over the western US toward the end of the
week, bringing another warming trend over the weekend.




Mainly VFR conditions the next 24 hours across interior NorCal,
except reduced visibilities in smoke near the Detwiler Fire. Winds
will remain light today, except gusts to 25 kt near the Delta and
over higher terrain.



Heat Advisory until 9 PM PDT Sunday for Central Sacramento
Valley-Mountains Southwestern Shasta County to Northern Lake
County-Northeast Foothills/Sacramento Valley-Northern Sacramento
Valley-Shasta Lake Area / Northern Shasta County.


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