DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 120831
SWODY3
SPC AC 120829

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CST WED DEC 12 2012

VALID 141200Z - 151200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
MODELS INDICATE THAT STRONG UPPER JET INTENSIFICATION WILL CONTINUE
ACROSS THE CENTRAL AND SOUTHERN TIER OF THE U.S. DURING THIS
FORECAST PERIOD. ACROSS THE PLAINS...THIS FLOW LIKELY WILL TREND
TOWARD WEST SOUTHWESTERLY...AS INITIAL SHORT WAVE RIDGING BREAKS
DOWN IN RESPONSE TO THE NORTHEASTWARD ACCELERATION OF A SIGNIFICANT
SHORT WAVE TROUGH AND EMBEDDED CLOSED LOW OUT OF THE SOUTHWESTERN
STATES. INCREASING SPREAD AMONG THE VARIOUS MODELS CONCERNING THE
DETAILS OF THIS PROCESS BY THURSDAY NIGHT DOES GROW THROUGH
FRIDAY/FRIDAY NIGHT. HOWEVER...IN GENERAL...GUIDANCE INDICATES THAT
A 90+ KT 500 MB SPEED MAXIMUM...NOSING THROUGH THE NORTHWESTERN
MEXICAN PLATEAU AT 12Z FRIDAY...WILL PROPAGATE INTO AND THROUGH THE
SOUTH CENTRAL PLAINS/OZARK PLATEAU REGION BY THE END OF THE PERIOD.
THIS FEATURE MAY WEAKEN IN STRENGTH AS IT DOES...BUT IT APPEARS THAT
STRONG MID-LEVEL HEIGHT FALLS WILL OVERSPREAD THE CENTRAL PLAINS
WITH A SURFACE LOW DEEPENING ACROSS SOUTHEAST COLORADO LATE FRIDAY
AFTERNOON...BEFORE MIGRATING NORTHEASTWARD TOWARD THE MID/LOWER
MISSOURI VALLEY.

FORCING FOR UPWARD VERTICAL MOTION AND COOLING IN THE EXIT REGION OF
THE JET PROBABLY WILL CONTRIBUTE TO A CONTINUING RISK FOR
THUNDERSTORM ACTIVITY ACROSS PARTS OF THE GREAT BASIN AND
CENTRAL/SOUTHERN ROCKIES INTO FRIDAY AFTERNOON. THEREAFTER...THE
PRIMARY CONVECTIVE POTENTIAL WILL SHIFT TO THE PLAINS AND PORTIONS
OF THE MISSOURI/MIDDLE MISSISSIPPI VALLEYS...IN RESPONSE TO THE
LARGE-SCALE FORCING. HOWEVER...AT LEAST THROUGH 12Z SATURDAY...
SIGNIFICANT GULF MOISTURE RETURN MAY NOT OCCUR IN TIME TO SUPPORT
MORE THAN LOW SEVERE WEATHER PROBABILITIES.

...SOUTHERN PLAINS INTO PARTS OF THE OZARK PLATEAU...
GUIDANCE REMAINS SUGGESTIVE THAT THE LACK OF BETTER PHASING BETWEEN
MID/UPPER FORCING FOR UPWARD VERTICAL MOTION AND BOUNDARY LAYER
DESTABILIZATION WILL HINDER THE RISK FOR SEVERE STORM DEVELOPMENT.
MID/UPPER 50S DEW POINTS MAY ONLY ADVECT AS FAR NORTH AS
SOUTHWESTERN OKLAHOMA/NORTHWEST TEXAS PORTIONS OF A DEVELOPING DRY
LINE BY EARLY FRIDAY EVENING...WHEN 60F+ SURFACE DEW POINTS MAY BE
IN THE PROCESS OF DEVELOPING NORTHWARD INTO CENTRAL TEXAS. THIS
APPEARS LIKELY TO BE GENERALLY SOUTH OF THE AXIS OF THE CYCLONIC
MID-LEVEL JET STREAK AS IT NOSES INTO THE SOUTH CENTRAL PLAINS.

HOWEVER...MOISTURE RETURN/DESTABILIZATION AND LIFT ABOVE A RESIDUAL
COOL/STABLE NEAR SURFACE LAYER IS EXPECTED TO SUPPORT ELEVATED STORM
DEVELOPMENT...WHICH COULD BE BECOME CAPABLE OF PRODUCING MARGINALLY
SEVERE HAIL...GENERALLY NORTH OF THE RED RIVER...ACROSS
OKLAHOMA...BEFORE SPREADING INTO ARKANSAS OVERNIGHT.

FARTHER SOUTH...IT MAY NOT BE OUT OF THE QUESTION THAT CONTINUED
NORTHWARD ADVECTION OF BOUNDARY LAYER MOISTURE...AND LIFT ASSOCIATED
WITH LOW-LEVEL WARM ADVECTION...COULD SUPPORT BOUNDARY LAYER BASED
OR NEAR BOUNDARY LAYER BASED STORM DEVELOPMENT ACROSS PARTS OF
NORTHERN TEXAS OVERNIGHT. IF THIS OCCURS...VERTICAL SHEAR WILL BE
MORE THAN SUFFICIENT FOR SUPERCELLS.

..KERR.. 12/12/2012

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