DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 170755
SWODY3
SPC AC 170753

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0153 AM CST SAT DEC 17 2011

VALID 191200Z - 201200Z

...SYNOPSIS...

CUTOFF UPPER LOW NOW SITUATED OVER NRN BAJA THAT IS PART OF A WRN
U.S. REX BLOCK WILL BEGIN TO EJECT EWD SUNDAY AND CONTINUE THROUGH
THE SRN PLAINS MONDAY. ATTENDANT SFC LOW WILL LIKELY MOVE ACROSS NRN
TX OR OK WITH TRAILING PACIFIC FRONT ADVANCING THROUGH THE REMAINDER
OF TX.

...CNTRL THROUGH ERN TX AND WRN LA...

STRONG 50-60 KT SLY LLJ ASSOCIATED WITH THE EJECTING UPPER LOW WILL
TRANSPORT PARTIALLY MODIFIED GULF AIR INTO THE SRN PLAINS MONDAY
WITH SFC DEWPOINTS FROM THE LOW-MID 60S ACROSS SRN-SERN TX TO MID
50S OVER N-NCNTRL TX. WRN EXTENSION OF SERN U.S. SFC RIDGE IS
FORECAST TO BE IN PLACE EARLY MONDAY OVER CNTRL/ERN TX. INCREASING
SLY FLOW AND ISENTROPIC ASCENT ABOVE THIS COOL...STABLE LAYER WILL
LIKELY RESULT IN WIDESPREAD LOW CLOUDS EARLY IN PERIOD...LIMITING
DESTABILIZATION POTENTIAL SOMEWHAT. NEVERTHELESS...LOW LEVEL THETA-E
ADVECTION AND POTENTIAL FOR SOME OF THE LOW CLOUDS MIXING OUT FROM
THE SOUTH DURING THE AFTERNOON MAY SUPPORT AN AXIS OF MARGINAL
INSTABILITY WITH MLCAPE GENERALLY AOB 500 J/KG.

A BAND OF STORMS WILL LIKELY BE IN PROGRESS WITHIN ZONE OF DEEPER
ASCENT ALONG WARM CONVEYOR BELT ACROSS WRN TX MONDAY MORNING. SOME
OF THE STORMS MAY INTENSIFY AND BECOME SURFACE BASED AS THEY BEGIN
TO INTERACT WITH THE MOISTENING AND DESTABILIZING BOUNDARY LAYER
FARTHER EAST. GIVEN DEGREE OF FORCING...PRIMARY CONVECTIVE MODE IS
EXPECTED TO BE LINEAR. HOWEVER...ACTIVITY WILL REMAIN EMBEDDED
WITHIN STRONG LOW-LEVEL AND DEEP SHEAR ACCOMPANYING THE SHORTWAVE
TROUGH AS IT PROGRESSES EWD...SUPPORTING POTENTIAL FOR EMBEDDED
ORGANIZED STRUCTURES. PRIMARY THREAT IS EXPECTED TO BE ISOLATED
DAMAGING WIND...BUT A COUPLE OF TORNADOES CANNOT BE RULED OUT.
THREAT WILL SHIFT INTO THE LOWER MS VALLEY OVERNIGHT. DUE TO
POTENTIAL LIMITING FACTORS WITHIN THERMODYNAMIC ENVIRONMENT...5%
PROBABILITIES WILL BE INTRODUCED AT THIS TIME...BUT A PORTION OF
THIS AREA MAY NEED TO BE UPGRADED TO A SLIGHT RISK IN LATER
OUTLOOKS.

..DIAL.. 12/17/2011

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