SWODY2
SPC AC 191713
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1113 AM CST WED DEC 19 2007
VALID 201200Z - 211200Z
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS E TX/LA EWD TO WRN FL
PANHANDLE...
..SYNOPSIS...
PROGRESSIVE AND AMPLIFIED SHORT WAVE TROUGH MOVING INTO THE SRN
PLAINS DURING DAY 1 PERIOD WILL TRACK EWD INTO THE LOWER MS VALLEY/
NWRN GULF BY LATE THURSDAY AFTERNOON /21/00Z/. THIS SYSTEM WILL
THEN MOVE EWD ACROSS THE CENTRAL GULF COAST STATES INTO THE SERN
U.S. THURSDAY NIGHT/EARLY FRIDAY MORNING. AT THE SURFACE...AN
ATTENDANT AREA OF LOW PRESSURE SHOULD BE LOCATED OVER THE LOWER RED
RIVER VALLEY OF NE TX/SE OK BY 20/12Z...AND THEN TRACK ENEWD INTO
NRN MS BY 21/00-06Z TIME FRAME. THIS LOW IS EXPECTED TO WEAKEN AS
IT MOVES INTO TN THURSDAY NIGHT AS IT ENCOUNTERS A DOWNSTREAM
SURFACE RIDGE OVER THE ERN UNITED STATES.
..SE TX TO CENTRAL GULF COAST REGION...
SHOWERS AND EMBEDDED TSTMS...SOME POSSIBLY STRONG TO SEVERE...WILL
LIKELY BE ONGOING ACROSS E TX/ARKLATEX REGION INTO THE LOWER MS
VALLEY AT 12Z THURSDAY. STRONG MID LEVEL DIFFLUENT FLOW REGIME/DPVA
AHEAD OF PROGRESSIVE SHORT WAVE TROUGH COMBINED WITH LOW LEVEL WAA
WILL MAINTAIN TSTM ACTIVITY DURING DAY 2 PERIOD EWD ACROSS LOWER MS
VALLEY TO CENTRAL GULF COAST STATES. STRONG SSWLY LLJ AT 45-55 KT
WILL SUPPORT MOISTURE INFLUX INTO THIS REGION WITH SURFACE DEWPOINTS
IN THE LOWER-MID 60S. THIS COMBINED WITH MID LEVEL COOLING/STEEP
LAPSE RATES WILL RESULT IN A MODERATELY UNSTABLE AIR MASS ACROSS THE
CATEGORICAL RISK AREA. STRONG SSWLY LLJ BENEATH 50 KT WSWLY MID
LEVEL WINDS WILL SUPPORT SUFFICIENTLY STRONG DEEP LAYER SHEAR FOR
BOTH EMBEDDED SUPERCELLS AND BOW STRUCTURES AS ACTIVITY DEVELOPS
EWD. MODELS CONTINUE TO INDICATE SEVERE POTENTIAL EFFECTIVELY BEING
SHUNTED SEWD WITH TIME...AS STRONGEST DEEP-LAYER FORCING OUTRUNS
MOST FAVORABLE BOUNDARY LAYER DESTABILIZATION.
FARTHER N INTO AR/NRN MS...MOISTURE RETURN WILL BE LESS AND THUS
RESULT IN WEAKER INSTABILITY. HOWEVER...THIS COMBINED WITH MODEST
DEEP LAYER SHEAR SHOULD SUPPORT AN ISOLATED THREAT FOR A FEW STRONG
TO SEVERE TSTMS PRODUCING MAINLY HAIL AND STRONGER WIND GUSTS.
.PETERS.. 12/19/2007
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