DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 130533
SWODY1
SPC AC 130531

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1131 PM CST WED DEC 12 2012

VALID 131200Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SWRN U.S...

LATE EVENING WV IMAGERY CLEARLY DEPICTS A DIGGING UPPER TROUGH ALONG
THE CA COAST. THIS FEATURE IS EXPECTED TO DROP CONSIDERABLY SOUTH
BEFORE FLOW INCREASES WITHIN THE BASE OF THE TROUGH AND FORCES THE
SYSTEM TO EJECT EWD. LATEST MODEL GUIDANCE SUGGEST A VERY STRONG
MID LEVEL SPEED MAX WILL ROTATE INLAND ACROSS THE CNTRL BAJA
PENINSULA DURING THE EVENING HOURS BEFORE ADVECTING INTO NWRN
MEXICO. THIS ENERGETIC UPPER SYSTEM WILL UNDOUBTEDLY ENCOURAGE
CONVECTION SOUTH OF THE U.S. BORDER OVER PORTIONS OF THE BAJA
PENINSULA AND NWRN MEXICO AS STRONG HEIGHT FALLS/DIFFLUENT FLOW
ALOFT SPREAD ACROSS A REGION OF MODEST INSTABILITY AND STEEPENING
LAPSE RATES. IT/S NOT ENTIRELY CLEAR WHETHER MEANINGFUL MOISTURE
WILL SPREAD NORTH OF THE BORDER BUT SFC DEW POINTS ARE EXPECTED TO
RISE ACROSS THE LOWER CO RIVER VALLEY SUCH THAT SCT TSTMS SHOULD
ULTIMATELY DEVELOP DURING THE EVENING/OVER NIGHT HOURS...AHEAD OF
THE COLD FRONT...AS STRONG FORCING APPROACHES. FORECAST SOUNDINGS
SUGGEST 200-400 J/KG NEAR-SBCAPE COULD DEVELOP NEAR THE
BORDER...COINCIDENT WITH STRONG DEEP LAYER SHEAR THAT WOULD
OTHERWISE FAVOR SUSTAINED UPDRAFTS. WILL NOT INTRODUCE SEVERE PROBS
ACROSS THIS REGION ATTM HOWEVER STRONG/SEVERE THUNDERSTORMS WILL
LIKELY DEVELOP ACROSS PORTIONS OF NWRN MEXICO. IF
MOISTURE/INSTABILITY INCREASE ACROSS SRN AZ MORE THAN MODELS
INDICATE THEN SEVERE THREAT WILL INCREASE ACCORDINGLY. FOR NOW THE
GREATEST RISK WILL BE MARGINAL WIND/HAIL WITH STRONGLY SHEARED AND
FAST MOVING BUT WEAKLY BUOYANT PRE-FRONTAL CONVECTION.

..DARROW/LEITMAN.. 12/13/2012

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