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000
FXUS66 KSTO 142222
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
322 PM PDT TUE MAY 14 2013

.SHORT TERM DISCUSSION...

SCATTERED THUNDERSTORMS OVER THE SIERRA WILL END THIS EVENING.
THE NEXT LOW PRESSURE SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA
THURSDAY AND FRIDAY...BRINGING A BETTER CHANCE OF PRECIPITATION
MAINLY ALONG THE MOUNTAINS BUT POSSIBLY DOWN TO THE VALLEY FLOOR.

NOW AND TONIGHT...
A COMPACT UPPER LOW IS TRAVERSING ACROSS CENTRAL CALIFORNIA
TODAY. THIS SYSTEM HAS BROUGHT STRONG LIFT AND INSTABILITY TO THE
SIERRA CREST THIS AFTERNOON. THE STRONGEST STORM THAT HAS FORMED
THUS FAR WAS NEAR LAKE ALPINE...AND HAD A SPOTTER REPORT OF
QUARTER-SIZED HAIL. THESE THUNDERSTORMS ARE EXPECTED TO CONTINUE
THROUGH LATE AFTERNOON OR EARLY EVENING BEFORE THE BEST DYNAMICS
SHIFT EASTWARD. TEMPERATURES ARE PEAKING IN THE UPPER 80S TO MID
90S ACROSS THE VALLEY THIS AFTERNOON...WITH 60S TO 80S OVER THE
MOUNTAINS. FAIR WEATHER AND MOSTLY CLEAR SKIES SHOULD PREVAIL
TONIGHT.

WEDNESDAY...
BROAD WESTERLY FLOW WILL DOMINATE IN THE WAKE OF TODAYS CLOSED
LOW. THE COMBINATION OF SOME SYNOPTIC COOLING AND GREATER CLOUD
COVER SHOULD BRING COOLER TEMPERATURES TO THE FORECAST AREA. LOOK
FOR HIGHS IN THE MID 80S ACROSS THE VALLEY...WHICH IS STILL A FEW
DEGREES WARMER THAN NORMAL.

THURSDAY AND FRIDAY...
BY EARLY THURSDAY MORNING A TROUGH WILL BEGIN TO MOVE THROUGH THE
PACIFIC NORTHWEST. THIS SYSTEM TAPS INTO A DECENT MOISTURE PLUME
ORIGINATING FROM THE CENTRAL PACIFIC. DYNAMICS ARENT OVERLY
IMPRESSIVE...BUT THE SYSTEM SHOULD BE ABLE TO GENERATE AT LEAST
SCATTERED SHOWERS AND POSSIBLY THUNDERSTORMS THURSDAY AND FRIDAY
ESPECIALLY OVER THE MOUNTAINS. SNOW LEVELS SHOULD REMAIN ABOVE THE
MAJOR PASSES... BUT THE PEAKS ABOVE 7500 FT COULD SEE MINOR SNOW
ACCUMULATIONS. WOULDNT BE SURPRISING FOR SOME SHOWERS TO OCCUR
OVER THE VALLEY AS WELL... BUT CLIMATOLOGICALLY SPEAKING IT
BECOMES INCREASINGLY DIFFICULT FOR PRECIPITATION TO REACH THE
VALLEY FLOOR THIS TIME OF YEAR. DANG


.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)

A LITTLE MORE SPREAD AND A LITTLE MORE TROFFING IN THE ECMWF MODEL
ON SAT RESULTS IN A LITTLE MORE UNCERTAINTY IN THE FORECAST FOR THE
NRN ZONES...OTHERWISE WARMING AND DRYING OCCURS THROUGH THE WEEKEND.
EARLY NEXT WEEK (MON/TUE) A DEEP CLOSED LOW IS FORECAST TO DEVELOP
OFF THE B.C. OR PAC NW COAST DEPENDING ON THE MODEL...WITH THE GFS
THE FARTHEST SOUTH ON TUE. AFTER A WARM WEEKEND CONTINUING INTO
MON...A COOLING TREND IS EXPECTED ON TUE AS LOWERING HEIGHTS AND
INCREASING ONSHORE FLOW RESULT IN DEEP SYNOPTIC COOLING ON TUE. WE
HAVE BLENDED THE MAX TEMPS FOR TUE...WITH THE POSSIBILITY FOR
FURTHER COOLING IF THE PATTERN HOLDS. OTHERWISE...THE PRECIP FROM
THIS DEEP CLOSED LOW IS FORECAST TO MAINLY STAY N OF NORCAL WITH
STRONG AND DRY WSWLY FLOW INTO OUR CWA RAISING FIRE WX CONCERNS
DUE TO STRENGTHENING WINDS OVER THE HIGHER TERRAIN AND DRY/DRYING
FUELS...ALBEIT THERE WILL BE SOME RELIEF FROM THE COOLER TEMPS.
   JHM



&&

.AVIATION...

MAINLY VFR SKC CONDITIONS OVER TAF SITES WITH INCREASE IN HIGH CLOUD
COVER AFT 12Z WED WITH BASES ABV 15 KFT THRU 00Z THU. OVER
SIERNEV...SCATTERED RASH/TSRA/TSRAGS DISSIPATING AFTER SUNSET WITH
UPPER LOW MOVING EWD. DELTA BREEZE FORECAST TO INCREASE TO 20-35 KTS
THROUGH THE CARQUINEZ STRAIT THIS EVENING AND OVERNITE...AND INTO
THE INTERIOR VALLEY 5-15 KTS OVERNITE. MARINE LAYER IS WELL MIXED
OUT OFF THE COAST...AND ANY STRATUS THAT FORMS IS EXPECTED TO BE
CONFINED TO THE COAST OR COASTAL VALLEYS.

&&

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

$$