DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281311
SWODY1
SPC AC 281308

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0708 AM CST FRI NOV 28 2008

VALID 281300Z - 291200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A MID LEVEL SHORTWAVE TROUGH OVER THE SRN HIGH PLAINS THIS MORNING
WILL EJECT EWD TO THE LOWER MS VALLEY TONIGHT. THIS WAVE IS
EXPECTED TO LOSE AMPLITUDE WITH TIME IN A CONFLUENT FLOW
REGIME...WHILE AN UPSTREAM TROUGH OVER THE NRN ROCKIES DIGS SEWD TO
THE CENTRAL ROCKIES AND HIGH PLAINS. IN ADVANCE OF THE
WEAKENING/EJECTING MID LEVEL TROUGH...WEAK CYCLOGENESIS WILL OCCUR
TODAY ALONG A BAROCLINIC ZONE ACROSS SE TX...AND THIS WEAK CYCLONE
WILL DEVELOP ENEWD TO CENTRAL MS BY EARLY SATURDAY. THE PRIMARY
FOCUS FOR DEEP CONVECTION THIS PERIOD WILL BE ALONG THE BAROCLINIC
ZONE AND THE PATH OF THE WEAK SURFACE LOW FROM SE TX INTO CENTRAL
MS/AL.

...SE TX/SRN LA/CENTRAL/SRN MS THROUGH EARLY SATURDAY...
LOW-LEVEL MOISTURE HAS INCREASED GRADUALLY DURING THE PAST 12-24
HOURS ACROSS THE NW GULF COAST...WHERE SURFACE DEWPOINTS ARE NOW IN
THE MID-UPPER 60S FROM THE TX COASTAL PLAIN INTO SW LA. THIS
MOISTURE WILL SPREAD GRADUALLY ENEWD INTO SRN/CENTRAL MS AND AL
THROUGH TONIGHT. RELATIVELY POOR MID LEVEL LAPSE RATES WILL TEND TO
LIMIT THE OVERALL DEGREE OF INSTABILITY OVER THE LOWER MS
VALLEY...AND LOW-LEVEL FLOW/SHEAR MAGNITUDES WILL LIKEWISE BE
LIMITED BY THE DEAMPLIFICATION OF THE MID LEVEL TROUGH AND ONLY WEAK
SURFACE CYCLOGENESIS. THE RESULTANT WARM SECTOR WILL BE
CHARACTERIZED BY SUFFICIENT DEEP LAYER SHEAR FOR SUPERCELLS
/EFFECTIVE BULK SHEAR OF 40-50 KT/...BUT RATHER MODEST LOW-LEVEL
SHEAR /EFFECTIVE SRH AOB 150 M2/S2/ AND INSTABILITY /MLCAPE OF
500-1000 J/KG/.

ONGOING CONVECTION FROM E TX INTO CENTRAL MS WILL LIKELY INCREASE IN
COVERAGE ALONG THE BAROCLINIC ZONE AS THE BOUNDARY LAYER
MOISTENS/DESTABILIZES S OF THE BOUNDARY DURING THE DAY. A FEW
EMBEDDED SUPERCELLS WILL BE POSSIBLE LATER TODAY INTO TONIGHT ALONG
THE FRONT FROM SE TX ENEWD INTO MS...WHERE THE STRONGER STORMS COULD
PRODUCE ISOLATED DAMAGING WINDS AND PERHAPS A TORNADO.

..THOMPSON/HURLBUT.. 11/28/2008

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