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000
FXUS66 KSTO 201130
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
430 AM PDT MON MAY 20 2013

.DISCUSSION...
MILDER TEMPERATURES ACROSS THE INTERIOR OF NORCAL EARLY THIS
MORNING AS UPPER RIDGE APPROACHES AND NORTHERLY WINDS CONTINUE IN
THE CENTRAL VALLEY WITH EASTERLY WINDS IN THE NORTHERN SIERRA
NEVADA. MOST AREAS ARE RUNNING AROUND 3 TO 8 DEGREES WARMER
COMPARED TO 24 HOURS AGO...BUT TRAVIS AFB AND VACAVILLE ALONG THE
WEST SIDE OF THE VALLEY ARE ABOUT 20 DEGREES WARMER THAN EARLY
SUNDAY AS BREEZY NORTH WINDS AS BREEZY NORTH WINDS CONTRIBUTE TO
ADIABATIC WARMING AS FLOW DESCENDS FROM THE COASTAL HILLS.

UPPER RIDGE SHIFTS OVER NORCAL TODAY WHICH WILL RESULT IN THE
WARMEST TEMPERATURES OF THE WEEK AS NORTH AND EAST WINDS DROP OFF
AND THE OVERALL AIRMASS CONTINUES TO WARM. HIGHS IN THE VALLEY ARE
EXPECTED TO CLIMB INTO THE LOWER 90S WHILE THE MOUNTAINS WILL BE
MAINLY IN THE UPPER 60S AND 70S.

A MAJOR CHANGE TOWARD COOLER AND BREEZIER WEATHER IS FORECAST TO
BEGIN TUESDAY AS THE UPPER LOW PRESENTLY CENTERED OVER THE
SOUTHERN YUKON TERRITORY DROPS SOUTHEASTWARD INTO THE PACNW AND
CLOSES OFF. THE COLD UPPER LOW IS FORECAST TO BE JUST OFFSHORE THE
MOUTH OF THE COLUMBIA RIVER BY LATER TUESDAY...THEN ONLY SHIFTING
SLIGHTLY EAST BY WEDNESDAY. APPEARS AT THIS TIME THAT THIS SYSTEM
WILL BE RELATIVELY DRY FOR NORCAL WITH SHOWER CHANCES MAINLY
LIMITED TO THE MOUNTAINS NORTH OF REDDING WHILE THE MAIN IMPACTS
WILL BE MUCH COOLER TEMPERATURES AND BREEZY CONDITIONS FOR MID-
WEEK.

BY NEXT WEEKEND...THE CLOSED LOW WEAKENS INTO AN OPEN WAVE ALONG
THE WEST COAST. ADDITIONAL WEAK SHORTWAVES LOOK TO MOVE ONSHORE TO
NORCAL BRINGING THE POSSIBILITY OF ISOLATED SHOWERS TO THE
MOUNTAINS AROUND THE NORTHERN SAC VALLEY. TEMPERATURES ARE
FORECAST TO WARM SOMEWHAT...BUT WILL REMAIN A LITTLE BELOW NORMAL.

&&

.AVIATION...
VFR CONDS CONT. NORTH WINDS PERSIST THIS MORNING FOR THE SAC VLY
BUT NOT AS STRONG AS SUNDAY. GENERALLY AROUND 10 KTS WITH OCNL
GUSTS UP TO 15 KTS FOR KRDD...KRBL...KSMF...KSAC AND KMHR. WIND
DIRECTION WILL SWITCH THIS EVENING (BETWEEN 00-03Z) TO SLY FLOW
RANGING 5-10 KTS FOR THOSE TAF SITES. FOR THE NRN SAN JOAQUIN
VALLEY...NW TO W WINDS AT 6-12 KTS.

OVR MTN RIDGETOPS...LIGHT TO MODERATE NORTH WINDS WILL TRANSITION
TO WLY TONIGHT. JBB

&&

.STO WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$