DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 110823
SWODY3
SPC AC 110821

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0221 AM CST TUE DEC 11 2012

VALID 131200Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE SPREAD AMONG THE MODEL ENSEMBLE DATA IS SIZABLE DURING THIS
FORECAST PERIOD CONCERNING SHORT WAVE DEVELOPMENTS WITHIN A STRONG
MID-LATITUDE JET PROPAGATING EASTWARD ACROSS THE PACIFIC. BUT FLOW
WILL REMAIN SPLIT TO ITS EAST...ACROSS THE PACIFIC COAST INTO NORTH
AMERICA...WITH AN AMPLIFIED SHORT WAVE TROUGH/CLOSED LOW IN THE
SOUTHERN STREAM...LIKELY ACROSS CALIFORNIA...BY 12Z THURSDAY. AND
IT APPEARS PROBABLE THAT ANOTHER SIGNIFICANT IMPULSE EMANATING FROM
THE UPSTREAM JET WILL APPROACH THE PACIFIC NORTHWEST COAST...
CONTRIBUTING THE EASTWARD ACCELERATION OF THE SOUTHERN BRANCH
TROUGH. AS THIS OCCURS...MODELS CONTINUE TO INDICATE INTERACTION
WITH A BELT OF WESTERLIES EMERGING FROM THE SUBTROPICAL EASTERN
PACIFIC...LEADING TO FURTHER UPPER JET INTENSIFICATION AROUND THE
BASED OF THE TROUGH THROUGH THE CREST OF DOWNSTREAM SHORT WAVE
RIDGING BUILDING THROUGH THE CENTRAL/ SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY.

IN RESPONSE TO THESE DEVELOPMENTS...A PLUME OF MID/HIGH-LEVEL
MOISTENING AND CLOUD COVER APPEARS LIKELY ACROSS THE MEXICAN PLATEAU
INTO THE SOUTHERN PLAINS...WHILE LOW-LEVEL RETURN FLOW COMMENCES OFF
THE WESTERN GULF OF MEXICO. SUBSTANTIVE BOUNDARY LAYER MOISTENING
PROBABLY WILL BE CONFINED TO FAR SOUTH TEXAS...BUT MOISTURE RETURN
ABOVE A RESIDUAL COOL/STABLE SURFACE LAYER MAY REACH PARTS OF
CENTRAL AND NORTHEAST TEXAS BY LATE THURSDAY NIGHT. EVEN SO...IT
SEEMS THAT THIS WILL COINCIDE WITH MID-LEVEL WARMING...WHICH IS
EXPECTED TO SUPPRESS THE DEVELOPMENT OF THUNDERSTORM ACTIVITY.
MEANWHILE...MID-LEVEL COOLING ACROSS PARTS OF THE GREAT BASIN INTO
SOUTHERN ROCKIES MAY CONTRIBUTE TO WEAK DESTABILIZATION SUFFICIENT
FOR SCATTERED THUNDERSTORM ACTIVITY THURSDAY AFTERNOON INTO THURSDAY
NIGHT.

..KERR.. 12/11/2012

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