DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 120741
SWODY3
SPC AC 120740

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0140 AM CST MON DEC 12 2011

VALID 141200Z - 151200Z

...SYNOPSIS...
MODELS ARE SIMILAR IN INDICATING THAT A 90-100+ KT 500 MB JET
STREAK...ASSOCIATED WITH A INCREASINGLY SHEARED UPPER IMPULSE
EMERGING FROM THE SOUTHWEST...WILL NOSE ACROSS THE CENTRAL PLAINS
AND UPPER PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY INTO THE GREAT
LAKES REGION DURING THIS PERIOD. THIS IS EXPECTED TO OCCUR AS
ANOTHER IMPULSE...WITHIN A MORE NORTHERN STREAM...DIGS ACROSS THE
CENTRAL CANADIAN/U.S. BORDER INTO THE UPPER MISSISSIPPI VALLEY...
AND A STRONGER UPSTREAM IMPULSE...WITHIN A SEPARATE STREAM...DIGS
INTO THE PACIFIC NORTHWEST.

VARIABILITY EXISTS AMONG THE GUIDANCE CONCERNING THE INFLUENCE AND
INTERACTION OF THESE FEATURES... PARTICULARLY CONCERNING THEIR
IMPACT ON POSSIBLE SIGNIFICANT SURFACE CYCLOGENESIS ACROSS THE
PLAINS INTO THE GREAT LAKES REGION. AND BOUNDARY LAYER
DESTABILIZATION WITHIN THE WARM SECTOR OF THE DEVELOPING LOW REMAINS
UNCLEAR. PRECIPITABLE WATER VALUES ASSOCIATED WITH AN INFLUX OF
MOISTURE OFF THE GULF OF MEXICO WILL BE SEASONABLY HIGH...BUT
EROSION OF A RESIDUAL COOL NEAR SURFACE LAYER MAY STILL BE AN ISSUE
ACROSS MUCH OF THE CENTRAL STATES.

NAM FORECAST SOUNDINGS ARE SUGGESTIVE THAT SURFACE WARMING AND
MOISTENING COULD BECOME SUFFICIENT FOR AT LEAST VERY WEAK BOUNDARY
LAYER DESTABILIZATION BY LATE WEDNESDAY AFTERNOON ALONG AN AXIS FROM
EASTERN KANSAS/WESTERN MISSOURI INTO CENTRAL TEXAS. IF THIS
OCCURS...LARGE-SCALE FORCING COULD SUPPORT ORGANIZED CONVECTIVE
DEVELOPMENT IN THE PRESENCE OF A VERY STRONG DEEP LAYER MEAN FLOW
AND SHEAR. LOW-LEVEL HODOGRAPHS ALONG A 50+ KT SOUTHWESTERLY 850 MB
JET AXIS ARE PROGGED TO GENERALLY POSSESS ONLY WEAK CLOCKWISE
CURVATURE...BUT SHEAR SHOULD BE STRONG ENOUGH TO POSE A RISK FOR
ISOLATED TORNADOES...IN ADDITION TO THE PRIMARY POTENTIAL FOR STRONG
SURFACE WIND GUSTS. THIS THREAT COULD DEVELOP EASTWARD ACROSS PARTS
OF THE MIDDLE MISSISSIPPI VALLEY AND OZARK PLATEAU...BEFORE
DIMINISHING LATE WEDNESDAY EVENING.

..KERR.. 12/12/2011

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