Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 201122

Area Forecast Discussion
National Weather Service Sacramento CA
422 AM PDT Tue Jun 20 2017

Extended heat wave continues with widespread highs over 100
degrees and warm nights. Isolated afternoon thunderstorms possible
over the mountains into mid-week.


Clear skies across interior NorCal early this morning. Current
temperatures are running around 3-6 degrees cooler compared to 24
hours ago and generally range from the upper 40s and 50s in the
mountain valleys to the 60s and 70s elsewhere except for some
lower 80s in warmer portions of the Central Valley.

Delta breeze has made a very modest return with the marine layer
now around 1K ft deep. This will help keep valley readings close
to Monday`s with Delta perhaps a few degrees cooler.

Very weak trough along with lingering mid/upper level moisture
combined with daytime heating over the higher terrain will lead to
more isolated late-day thunderstorms over the NorCal mountains
today and Wednesday.

High pressure strengthens again Wednesday into Thursday and will
suppress the Delta Breeze leading to warmer temperatures. It will
also likely limit thunderstorms to the Sierra south of Tahoe. In
addition, north winds will set up in the valley, especially on the
western side on Wednesday and Thursday. Those winds, coupled with
dry conditions will enhance fire weather concerns.

Some record highs are listed below.
Record Highs...........Tuesday....Wednesday..Thursday....Friday
Redding City...........109(1961)..108(1961)..109(1970)..109(1925)
Redding Apt............107(2001)..110(1992)..107(2006)..111(2006)
Red Bluff..............110(1970)..110(1962)..111(1970)..112(2006)
Sacramento Exec........109(1961)..111(1961)..106(1968)..105(2006)


A NW to SE orientated long wave ridge in place over NorCal
through the weekend with a weak short wave trough that passes
through on Sunday which may bring instability to the area. At the
least, temperatures will cool as a Delta breeze looks to develop
late this weekend. Monday and Tuesday continue the cooling trend
and onshore flow as the longwave ridge shifts into the Great Basin
and a longwave trough works its way closer to the coast. JClapp


VFR conditions expected at the TAF sites the next 24 hours. SW
gusts 15 to 25 kts in the Delta. Potential isolated thunderstorms
over Coastal Range in Glenn county this afternoon. JClapp


Heat Advisory until 8 PM PDT Thursday for Clear Lake/Southern
Lake County-Motherlode-Mountains Southwestern Shasta County to
Northern Lake County-Northeast Foothills/Sacramento Valley-
Shasta Lake Area / Northern Shasta County-West Slope Northern
Sierra Nevada-Western Plumas County/Lassen Park.

Fire Weather Watch from Wednesday afternoon through Thursday
evening for Central Sacramento Valley in Glenn, Colusa, Yuba,
Northern Sutter, and Butte County Below 1000 Ft-Eastern
Mendocino NF-Eastern Portion of Shasta/Trinity NF-Lake County
Portion of Lake-Napa-Sonoma Unit-Northern Sacramento Valley to
Southern Tehama County Line Below 1000 Ft-Northern Sierra
Foothills from 1000 to 3000 Ft. Includes portions of Shasta-
Trinity and Butte Units-Southeast Edge Shasta-Trinity NF and
Western Portions of Tehama-Glenn Unit-Southern Sacramento Valley
in Yolo-Sacramento Far Western Placer, southern Sutter and
Solano County Below 1000 Ft.

Excessive Heat Warning until 8 PM PDT Thursday for Carquinez
Strait and Delta-Central Sacramento Valley-Northern Sacramento
Valley-Northern San Joaquin Valley-Southern Sacramento Valley.


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