DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 120601
SWODY2
SPC AC 120600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CST WED DEC 12 2012

VALID 131200Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE SPREAD AMONG THE VARIOUS MODEL ENSEMBLE DATA REMAINS LARGE FOR
THIS FORECAST PERIOD CONCERNING SHORT WAVE DEVELOPMENTS WITHIN A
STRONG MID-LATITUDE JET PROPAGATING EASTWARD ACROSS THE PACIFIC.
THIS INCLUDES ONE IMPULSE FORECAST TO EMERGE FROM THE JET AND
PROGRESS THROUGH AMPLIFIED UPPER RIDGING ACROSS THE NORTHEAST
PACIFIC...BEFORE DIGGING TOWARD THE BRITISH COLUMBIA AND PACIFIC
NORTHWEST COAST. IN THE PROCESS...THIS FEATURE APPEARS LIKELY TO
SPLIT...WITH ONE PORTION MIGRATING EASTWARD IN A ZONAL BRANCH OF
FLOW EXTENDING EASTWARD INTO CANADA...WHILE ANOTHER PORTION
CONTINUES TO DIG IN A BRANCH TO THE SOUTH...CURVING INTO A
SIGNIFICANT UPPER TROUGH ACROSS THE CALIFORNIA COAST.

VARIABILITY EXISTS AMONG THE MODELS CONCERNING THE
MAGNITUDE/EVOLUTION OF THE PERTURBATIONS EVOLVING OUT OF THE
SPLIT...AND THIS BEGINS TO INCREASE THE SPREAD CONCERNING THE
EASTWARD ACCELERATION AND EVOLUTION OF THE CALIFORNIA TROUGH AND
EMBEDDED CLOSED LOW. THIS LATTER SYSTEM DOES STILL APPEAR LIKELY TO
PROGRESS INTO THE GREAT BASIN AND SOUTHERN U.S./NORTHWESTERN MEXICAN
PLATEAU...WHILE INTERACTING WITH ANOTHER BELT OF WESTERLIES EMERGING
FROM THE SUBTROPICAL EASTERN PACIFIC. AS IT DOES...STRONG UPPER JET
INTENSIFICATION IS FORECAST ACROSS THE NORTHERN MEXICAN PLATEAU INTO
THE CREST OF AMPLIFYING SHORT WAVE RIDGING ACROSS THE SOUTHERN
PLAINS.

IN RESPONSE TO UPPER DEVELOPMENTS AND ASSOCIATED SURFACE PRESSURE
FALLS ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS...A RETURN FLOW OF
LOW-LEVEL MOISTURE MAY COMMENCE OFF THE WESTERN GULF OF MEXICO...
WHILE A PLUME OF HIGH LEVEL MOISTURE ADVECTS EAST NORTHEASTWARD
ALONG THE SOUTHEASTERN FRINGE OF THE UPPER JET. SUBSTANTIVE
BOUNDARY LAYER MOISTENING IS NOT EXPECTED INTO DEEP SOUTH TEXAS
UNTIL LATE IN THE PERIOD...BUT MAY OCCUR ABOVE A RESIDUAL COOL
STABLE SURFACE-BASED LAYER AS FAR NORTH AS PARTS OF CENTRAL AND
NORTHERN TEXAS. HOWEVER...LOWER/MID TROPOSPHERIC WARMING ABOVE THIS
LAYER PROBABLY WILL CAP POTENTIAL DESTABILIZATION. AS A
RESULT...CONVECTIVE POTENTIAL ACROSS THE SOUTHERN PLAINS IS EXPECTED
TO REMAIN NEGLIGIBLE THURSDAY AND THURSDAY NIGHT. WITH THE POSSIBLE
EXCEPTION OF A LINGERING RISK FOR THUNDERSTORMS NEAR SOUTHEAST
FLORIDA COASTAL AREAS...THIS WILL ALSO BE THE CASE ELSEWHERE EAST OF
THE PLAINS.

...GREAT BASIN/SOUTHERN PLATEAU/ROCKIES...
SIGNIFICANT MOISTENING IS FORECAST ACROSS THE REGION ON SOUTHERLY
LOW-LEVEL FLOW AHEAD OF THE UPPER TROUGH. IN CONJUNCTION WITH
BOUNDARY LAYER WARMING AND MID-LEVEL COOLING WITH THE APPROACH OF
THE TROUGH...AT LEAST WEAK DESTABILIZATION IS EXPECTED. COUPLED
WITH LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION...THIS SHOULD BE
SUFFICIENT FOR THE DEVELOPMENT OF SCATTERED THUNDERSTORMS LATE
THURSDAY INTO THURSDAY NIGHT. HIGHEST PROBABILITIES APPEAR TO EXIST
ALONG AND SOUTH OF THE MOGOLLON RIM...ACROSS THE LOWER DESERTS
AROUND PHOENIX. HOWEVER...THE RISK FOR THUNDERSTORMS MAY NOT BE
NEGLIGIBLE ACROSS PARTS OF EASTERN NEVADA INTO WESTERN UTAH...AND
NORTHEAST OF THE RIM...INTO THE FOUR CORNERS REGION AND THE
SOUTHWESTERN TWO-THIRDS OR SO OF NEW MEXICO LATE THURSDAY NIGHT.

..KERR.. 12/12/2012

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