SPC AC 270422
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1022 PM CST THU NOV 26 2009
VALID 281200Z - 291200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
A MID LEVEL TROUGH NOW OFF THE ORE/NRN CA COASTS WILL DIG SEWD OVER
SRN CA TOMORROW INTO EARLY SATURDAY. COOLING TEMPERATURES ALOFT
WITH THE ARRIVAL OF THE MID LEVEL COLD POOL AND CONDITIONALLY
UNSTABLE LOW-MID LEVEL LAPSE RATES WILL CONTRIBUTE TO THE POTENTIAL
FOR WEAK INSTABILITY WITH THIS SYSTEM ACROSS PARTS OF SRN CA AND
AZ/NM. THE SPECIFIC THUNDERSTORM THREATS SHOULD BE FOCUSED IN TWO
AREAS...THE SRN CA COAST NEAR THE COLD CORE LOW...AND THE WARM
CONVEYOR BELT ACROSS AZ BEGINNING IN THE AFTERNOON AND CONTINUING
INTO THE EARLY OVERNIGHT HOURS IN WRN NM.
...SWRN STATES...
WEAK ONSHORE FLOW ACROSS THE SRN CA COAST WITH BOUNDARY LAYER
DEWPOINTS IN THE MID-UPPER 40S AND 500 MB TEMPERATURES AOB -25 C
WILL SUPPORT SBCAPE VALUES IN THE RANGE OF 100-300 J/KG DURING THE
AFTERNOON/EVENING. ISOLATED LOW-TOPPED THUNDERSTORMS WILL BE
POSSIBLE NEAR THE COAST AND OVER THE IMMEDIATE OFFSHORE WATERS...AND
PERHAPS SOME SMALL HAIL...BEFORE THE MID LEVEL LOW REACHES NRN BAJA
LATE IN THE PERIOD. FARTHER E...DESTABILIZATION IS EXPECTED DURING
THE DAY ACROSS AZ/WRN NM WHERE MODEST LOW-MID LEVEL MOISTENING WILL
OCCUR FROM THE S...IN CONJUNCTION WITH COOLING MID LEVEL
TEMPERATURES AND STEEP LAPSE RATES. THE NET RESULT WILL BE AN
ENVIRONMENT SUPPORTIVE OF ISOLATED TO WIDELY SCATTERED THUNDERSTORMS
IN A LOOSE COMMA CONFIGURATION WITH THE BAND OF ASCENT TO THE E/NE
OF THE MID LEVEL LOW.
...ELSEWHERE...
A MODIFYING CONTINENTAL AIR MASS WILL RETURN NWD TO S AND E TX FROM
THE WRN GULF OF MEXICO...AND LOW-LEVEL MOISTENING SHOULD BE
SUFFICIENT FOR AT LEAST WEAK INSTABILITY. HOWEVER...ANY
THUNDERSTORM THREAT SHOULD BE DELAYED UNTIL BEYOND DAY 2 AS A RESULT
OF A CAPPED BOUNDARY LAYER AND ONLY WEAK FORCING FOR ASCENT AS THE
REMNANTS OF THE WEAK UPPER TROUGH NOW OVER NW MEXICO EJECT ENEWD
OVER THE NW GULF COAST THE FIRST HALF OF THE PERIOD.
..THOMPSON.. 11/27/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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