SPC AC 221621
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1021 AM CST WED DEC 22 2010
VALID 221630Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SRN CA TODAY TO THE LOWER CO VALLEY THROUGH THIS EVENING...
A MIDLEVEL SHORTWAVE TROUGH NEAR 32 N AND 132 W WILL MOVE INLAND
OVER SRN CA TODAY AND REACH WRN AZ TONIGHT. BOUNDARY LAYER
DEWPOINTS IN THE LOW-MID 50S HAVE OVERSPREAD SRN CA AND SW AZ IN
ADVANCE OF THE PRIMARY BAROCLINIC BAND WITH THE MIDLEVEL
TROUGH...AND THE MIDLEVEL COLD POOL WILL SPREAD INLAND OVER SRN CA
THIS AFTERNOON. COOLING ALOFT AND MAINTENANCE OF THE LOW-LEVEL
MOISTURE...ALONG WITH SURFACE HEATING IN CLOUD BREAKS...WILL
CONTRIBUTE TO AFTERNOON MLCAPE VALUES OF 250-500 J/KG. DEEP-LAYER
VERTICAL SHEAR WILL BE MOST FAVORABLE FOR ORGANIZED SEVERE STORMS IN
THE PRE-FRONTAL ENVIRONMENT WHERE INSTABILITY WILL BE QUITE WEAK.
HOWEVER...AT LEAST MARGINALLY FAVORABLE VERTICAL SHEAR WILL PERSIST
OVER SRN CA THIS AFTERNOON ON THE CYCLONIC SIDE OF THE MIDLEVEL
JET...AND LOW-LEVEL SHEAR SHOULD BE ENHANCED SOME BY CHANNELED
SLY/SELY SURFACE WINDS TO THE W OF THE MOUNTAINS. ISOLATED
STRONG/DAMAGING GUSTS AND A WATERSPOUT/TORNADO COULD OCCUR THIS
AFTERNOON NEAR THE COAST.
LATER THIS AFTERNOON/EVENING...THE THUNDERSTORM THREAT WILL INCREASE
FARTHER E INTO THE LOWER CO RIVER VALLEY OF SE CA AND SW AZ.
THUNDERSTORMS ARE EXPECTED IN A BAND ALONG THE COLD FRONT...W OF THE
ONGOING RAIN SHIELD. ISOLATED STRONG/DAMAGING GUSTS WILL BE THE
MAIN SEVERE THREAT WITH THIS ACTIVITY...PRIOR TO WEAKENING OF THE
INSTABILITY OVERNIGHT.
..THOMPSON/ROGERS.. 12/22/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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