DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 181723
SWODY2
SPC AC 181721

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CST TUE DEC 18 2007

VALID 191200Z - 201200Z

..THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF ERN TX INTO THE
LOWER MS VALLEY...

..SYNOPSIS...

SYNOPTIC PATTERN WILL REMAIN PROGRESSIVE THIS PERIOD. UPPER TROUGH
NOW APPROACHING WRN U.S. COAST WILL ADVANCE INTO THE CNTRL AND SRN
PLAINS WEDNESDAY NIGHT ACCOMPANIED BY A PACIFIC FRONT. THE FRONT
SHOULD EXTEND FROM A WEAK LEE LOW OVER OK SSWWD INTO SWRN TX BY THE
END OF THIS PERIOD. WARM FRONT WILL LIKELY DEVELOP INLAND AND EXTEND
SEWD FROM THE LOW THROUGH THE LOWER MS VALLEY WEDNESDAY NIGHT.

..ERN TX THROUGH LOWER MS VALLEY REGION...

SERN U.S. SURFACE HIGH WILL SHIFT EAST THROUGH WEDNESDAY...AND THIS
SHOULD EXPEDITE BOUNDARY LAYER RECOVERY OVER THE WRN GULF. LOW LEVEL
WINDS HAVE ALREADY SHIFTED TO SLY OFF THE TX COAST WITH LOW 60S
DEWPOINTS OBSERVED OVER DEEP SOUTH TX AND OFFSHORE. LOW LEVEL FLOW
WILL TEMPORARILY VEER TO WSWLY TUESDAY EVENING AS A LOW AMPLITUDE
UPPER TROUGH MOVES THROUGH THE PLAINS AND MS VALLEY. HOWEVER...THE
SLY LOW LEVEL JET WILL REDEVELOP OVER ERN TX WEDNESDAY EVENING IN
ADVANCE OF APPROACHING SHORTWAVE TROUGH. THIS WILL CONTRIBUTE TO
NEWD ADVECTION OF PARTIALLY MODIFIED GULF AIR. LOWER TO MID 60S
DEWPOINTS WILL LIKELY ADVECT INTO ERN TX AND THE LOWER MS VALLEY AS
THE WARM FRONT DEVELOPS INLAND. UPPER 60S DEWPOINTS WILL BE POSSIBLE
IN VICINITY OF THE TX AND LA COASTS. WSWLY FLOW DOWNSTREAM FROM
UPPER TROUGH WILL ADVECT STEEPER MID LEVEL LAPSE RATES OVER MOIST
AXIS...CONTRIBUTING TO DESTABILIZATION. MUCAPE FROM 500 TO 1000 J/KG
WILL BE POSSIBLE OVERNIGHT. INCREASING DEEP LAYER ASCENT AHEAD OF
UPPER TROUGH AND ALONG LOW LEVEL JET AXIS WILL RESULT IN DEVELOPMENT
OF THUNDERSTORMS WEDNESDAY NIGHT. MOST OF THE STORMS INLAND WILL
LIKELY BE ELEVATED ABOVE A SHALLOW SURFACE INVERSION WITH A THREAT
FOR MAINLY LARGE HAIL. HOWEVER...DEPENDING ON THE DEGREE OF MOISTURE
RETURN...SOME STORMS DEVELOPING NEAR THE COAST COULD BECOME SURFACE
BASED. EFFECTIVE SHEAR OF 40+ KT WILL BE SUPPORTIVE OF ORGANIZED
STORM STRUCTURES INCLUDING SUPERCELLS.

.DIAL.. 12/18/2007

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