Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 241043
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
343 AM PDT Sat Jun 24 2017

.SYNOPSIS...
HOT AGAIN TODAY EXCEPT FOR SIGNIFICANT COOLING IN THE DELTA AND
DELTA INFLUENCED AREAS OF THE SOUTHERN HALF OF THE SACRAMENTO
VALLEY, AND NORTHERN SAN JOAQUIN VALLEY. MORE SIGNIFICANT COOLING
FOR THE REMAINDER OF INTERIOR NORCAL EXPECTED SUNDAY INTO EARLY
NEXT WEEK. ISOLATED AFTERNOON/EVENING THUNDERSTORMS POSSIBLE OVER
THE MOUNTAINS THROUGH SUNDAY.

&&

.DISCUSSION...
UPPER LEVEL RIDGE AXIS WILL CENTER OVER THE WEST COAST TODAY
BRINGING CONTINUED HOT TEMPERATURES THIS AFTERNOON OVER THE
NORTHERN HALF OF THE CWA. THE SOUTHERN CWA WILL CONTINUE TO SEE
COOLING TODAY THANKS TO A SIGNIFICANT DELTA BREEZE EXPECTED TO
CONTINUE THROUGH THE DAY. THE HOTTEST TEMPERATURES TODAY WILL BE
IN THE NORTHERN SACRAMENTO VALLEY WHERE TEMPERATURES REACHING 110
DEGREES ARE FORECAST. THIS AREA IS ACTUALLY SEEING TEMPERATURES
SOMEWHAT COOLER THIS MORNING THANKS TO LIGHTER NORTH WINDS WHICH
HAS REDUCED THE ADIABATIC WARMING AFFECT. THE DELTA INFLUENCED
AREAS ARE SEEING A FEW TO SEVERAL DEGREES OF COOLING THIS MORNING
AS WELL. SATELLITE FOG PRODUCT SHOWS SOME COASTAL STRATUS MAKING
ITS WAY INTO THE DELTA THIS MORNING SO EARLY MORNING CLOUDINESS
WILL LIKELY IMPACT WESTERN SOLANO COUNTY. SOUTHERLY FLOW ALOFT AND
INSTABILITY WILL BRING ANOTHER THREAT OF AFTERNOON THUNDERSTORMS
OVER THE NORTHERN SIERRA TODAY. SOME INSTABILITY OVER THE COAST
RANGE MAY BRING A THREAT OF ISOLATED THUNDERSTORMS TODAY THERE AS
WELL.

UPPER RIDGE AXIS FINALLY SHIFTS INLAND ON SUNDAY WITH MAIN EFFECT
BEING A SIGNIFICANT COOLING. ALL AREAS OF THE CWA SHOULD SEE
ENOUGH COOLING TO FINALLY DROP ALL HEAT PRODUCTS FOR THE FIRST
TIME IN NEARLY A WEEK. COASTAL STRATUS IS LIKELY TO INTRUDE AGAIN
INTO THE DELTA MORNING HOURS WHILE SOUTHERLY FLOW AND INSTABILITY
WILL BRING ANOTHER THREAT OF AFTERNOON THUNDERSTORMS OVER THE
CRESTS OF THE SIERRA AND COAST RANGE. WEAK UPPER TROUGHING MOVES
OVER THE WEST COAST ON MONDAY BRINGING STILL MORE COOLING TO ALL
AREAS. AT THIS TIME IT APPEARS ANY SHOWER ACTIVITY ASSOCIATED
WITH THIS WEAK UPPER TROUGH WILL REMAIN NORTH OF THE FORECAST
AREA. LITTLE CHANGE IN TEMPERATURES EXPECTED ON TUESDAY AS WEAK
UPPER TROUGHING LINGERS OVER THE WEST COAST. STABLE WESTERLY FLOW
SHOULD KEEP THE ENTIRE CWA UNDER FAIR SKIES.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)

Trough will shift off to the east on Wednesday with the area
sandwiched between the trough to the east and high pressure to the
west for Thursday into Friday. Dry weather expected with plenty of
sunshine. Onshore flow will keep the Delta Breeze going. Rather
similar temperatures expected through Friday with high
temperatures within a few degrees of normal. Ridging starts to
build back in for next weekend, with a slight warming trend. Dry
weather expected with plenty of sunshine.  CEO

&&

.AVIATION...

VFR conditions expected at the TAF sites the next 24 hours.
Isolated thunderstorms possible over Sierra this afternoon south
of Lake Tahoe. Southwest winds up to 30 kt through the delta...
otherwise winds generally around 6-12 kts for TAF sites.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 11 PM PDT this evening for Central
Sacramento Valley-Clear Lake/Southern Lake County-Motherlode-
Shasta Lake Area / Northern Shasta County-Western Plumas
County/Lassen Park.

Excessive Heat Warning until 11 PM PDT this evening for
Mountains Southwestern Shasta County to Northern Lake County-
Northeast Foothills/Sacramento Valley-Northern Sacramento Valley.

&&

$$



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