Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 272203
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
303 PM PDT SAT JUN 27 2015

.SYNOPSIS...
NOT AS HOT THIS WEEKEND, THEN HEAT RETURNS NEXT WEEK. MOUNTAIN
THUNDERSTORM ACTIVITY THROUGH NEXT WEEK. THUNDERSTORMS WILL
INITIALLY HAVE LIMITED RAINFALL CREATING AN INCREASED FIRE THREAT.

&&

.DISCUSSION...
VARYING AMOUNTS OF MID AND HIGH CLOUDS CONTINUE TO STREAM
NORTHWARD INTO THE REGION AHEAD OF A WEAK CLOSED LOW OVER THE
EASTERN PACIFIC. THE MARINE LAYER IS CONTINUING TO DEEPEN AND IS
AROUND 2500 FT DEEP AT FT ORD AND ONSHORE GRADIENTS ARE
STRENGTHENING. BREEZY SOUTH WINDS HAVE DEVELOPED THROUGH MUCH OF
THE SACRAMENTO VALLEY AND TEMPERATURES THERE ARE RUNNING AROUND 10
DEGREES COOLER COMPARED TO 24 HOURS AGO. ELSEWHERE, TEMPERATURES
ARE ONLY SLIGHTLY COOLER COMPARED TO YESTERDAY.

THUNDERSTORM DEVELOPMENT SO FAR THIS AFTERNOON HAS BEEN EAST OF
THE CREST. BETTER CHANCES MAY DEVELOP OVER THE NORTHERN SIERRA AND
NORTHERN SACRAMENTO VALLEY TONIGHT AS A SHORT-WAVE PIVOTS
NORTHWARD AROUND THE OFFSHORE CLOSED LOW. MOISTURE REMAINS MAINLY
CONCENTRATED ABOVE ABOUT 500 MBS, SO BASES WILL BE HIGH AND ONLY
SPOTTY PRECIPITATION.

THE CHANCE OF MAINLY MOUNTAIN THUNDERSTORM ACTIVITY FOR NORCAL
WILL CONTINUE SUNDAY AS THE CLOSED LOW OPENS UP AND LIFTS NORTH
TOWARD THE PACIFIC NORTHWEST, THEN A COUPLE OF RELATIVELY QUIET
DAYS ARE EXPECTED FOR MONDAY AND TUESDAY.

THE COOL DOWN CONTINUES SUNDAY, THEN TEMPERATURES ARE FORECAST TO
BEGIN WARMING UP AGAIN ON MONDAY. BY TUESDAY, VERY HOT WEATHER IS
FORECAST TO RETURN TO NORCAL AS THE LARGE HIGH OVER THE WESTERN US
EXTENDS WESTWARD WITH READINGS THROUGH MUCH OF THE CENTRAL VALLEY
EXPECTED TO RETURN TO THE 105 TO 110 DEGREE RANGE.

&&

.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)...
HIGH PRESSURE WILL CONTINUE TO DOMINATE INTO NEXT WEEKEND.
EXPANSIVE UPPER LEVEL RIDGE CENTERED ACROSS FOUR CORNER REGIONS
WILL BUILD ACROSS THE AREA THROUGH THE END OF THE WORK WEEK WITH
WARMING TEMPERATURES. WELL ABOVE NORMAL TEMPERATES EXPECTED WITH
CENTRAL VALLEY TEMPERATURES INTO THE 100S AND NORTHERN VALLEY
AREAS TOPPING OUT IN EXCESS OF 110 DEGREES. THURSDAY LOOKS TO BE
THE HOTTEST DAY OF THE WEEK. OVERNIGHT LOWS WILL BE WARM AS WELL
WITH NORTHERN VALLEY LOCATIONS ONLY COOLING INTO THE MID 70S AND
INTO THE UPPER 60S ELSEWHERE IN THE VALLEY. THIS WILL LIKELY CAUSE
SOME HEAT IMPACTS AND RESIDENTS SHOULD ONCE AGAIN PREPARE FOR
PROLONGED HEAT. UPPER LEVEL HEIGHTS LOWER SOME BY SATURDAY AND
SUNDAY SO TEMPERATURES WILL COOL A FEW DEGREES FOR THE WEEKEND,
BUT AGAIN STILL MUCH ABOVE NORMAL WITH NO SIGNS OF A BIG COOL DOWN
FOR THE HOLIDAY WEEKEND. ALSO OF NOTE, DOMINANT HIGH PRESSURE WILL
CONTINUE S-SE FLOW AROUND THE RIDGE WHICH WILL ALLOW FOR THE
CONTINUED ADVECTION OF MONSOONAL MOISTURE INTO THE SIERRA AND
NORTHERN MOUNTAINS. THIS COMBINED WITH MOUNTAIN OROGRAPHICS AND
SUFFICIENT INSTABILITY SHOULD CONTINUE THE THREAT OF
AFTERNOON/EVENING THUNDERSTORMS ACROSS THE MOUNTAINS THROUGH AT
LEAST SATURDAY. CEO

&&

.AVIATION...
SOUTHERLY FLOW ALOFT AS NORCAL REMAINS BETWEEN HIGH PRESSURE OVER
THE FOUR CORNERS AREA AND A LOW OFFSHORE. VFR CONDITIONS OVER THE
INTERIOR NEXT 24 HOURS. SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS WITH MVFR CONDITIONS POSSIBLE OVER MOUNTAINS WITH
ASSOCIATED STRONG GUSTY SURFACE WINDS.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 10 PM PDT SUNDAY FOR BURNEY BASIN AND
NORTHEAST PLATEAU IN SHASTA COUNTY INCLUDING NORTHWEST LASSEN NF
NORTH OF LASSEN NP-NORTHERN SIERRA INCLUDING LASSEN NP AND
PLUMAS AND LASSEN NF/S WEST OF THE SIERRA CREST (WEST OF EVANS
PEAK-GRIZZLY PEAK-BECKWORTH PEAK)-NORTHERN SIERRA INCLUDING THE
TAHOE AND ELDORADO NF/S WEST OF THE SIERRA CREST-STANISLAUS NF
WEST OF THE SIERRA CREST.

&&

$$


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