SWODY1
SPC AC 280058
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0658 PM CST THU DEC 27 2007
VALID 280100Z - 281200Z
..NO SVR TSTM AREAS FORECAST...
..SOUTH CENTRAL STATES...
LOW-LEVEL WARM ADVECTION/CONVERGENCE CURRENTLY APPEARS MAXIMIZED
ALONG A TIGHTENING 850 MB BAROCLINIC ZONE...EXTENDING EAST
NORTHEASTWARD FROM PARTS OF CENTRAL/NORTHEAST TEXAS INTO PARTS OF
THE TENNESSEE VALLEY. HOWEVER...LOW-LEVEL MOISTURE LEVELS NEAR THIS
BOUNDARY ARE STILL TOO LOW...GIVEN THE RELATIVE WARMTH OF THE
MID-LEVEL ENVIRONMENT...TO SUPPORT DEEP CONVECTIVE DEVELOPMENT.
THE LEADING EDGE OF A MORE SIGNIFICANT LOW-LEVEL MOISTURE RETURN IS
JUST NOW BEGINNING TO SPREAD INTO MID/UPPER TEXAS COASTAL
AREAS...AND APPROACH THE LOUISIANA COAST. BUT...A SOUTHWESTERLY
LOW-LEVEL JET IS FORECAST TO STRENGTHEN IN EXCESS OF 50 KT NEAR THE
FRONTAL ZONE LATER THIS EVENING INTO THE OVERNIGHT HOURS.
AND...THIS IS EXPECTED TO CONTRIBUTE TO A MORE RAPID MOISTURE
RETURN. AS THIS OCCURS...INHIBITION IS EXPECTED TO WEAKEN
SUFFICIENTLY...IN THE ZONE OF STEEPER ISENTROPIC ASCENT ALONG/NORTH
OF THE BOUNDARY...FOR THE DEVELOPMENT OF SCATTERED THUNDERSTORMS.
WITH MODELS INDICATING MOST UNSTABLE CAPE APPROACHING OR EXCEEDING
500 J/KG...UPDRAFTS COULD BECOME VIGOROUS ENOUGH IN FAVORABLY COOL
THERMODYNAMIC PROFILES FOR HAIL PRODUCTION...THOUGH THIS SHOULD
MOSTLY REMAIN BELOW SEVERE LIMITS.
AS THE STRONG UPSTREAM SHORT WAVE IMPULSE CONTINUES TO LIFT
NORTHEAST OF THE SOUTHERN ROCKIES...TOWARD THE LOWER MISSOURI
VALLEY...A COUPLE OF WEAK THUNDERSTORMS APPEAR POSSIBLE THIS
EVENING. THIS MAY OCCUR AS THE MID-LEVEL COLD CORE/CIRCULATION
STRENGTHEN UPWARD VERTICAL MOTION NEAR A WARM FRONTAL ZONE EXTENDING
ACROSS THE SOUTHERN TEXAS PANHANDLE/NORTHWEST TEXAS.
OTHERWISE...A COLD FRONT IS EXPECTED TO EVENTUALLY SURGE ACROSS
TEXAS INTO THE SABINE VALLEY AND TEXAS COASTAL AREAS BY 12Z FRIDAY.
AND...THIS PROBABLY WILL BE ACCOMPANIED BY INCREASING THUNDERSTORM
ACTIVITY ALONG/JUST AHEAD OF IT. WITH COLDER AIR ALOFT LIFTING AWAY
FROM THE WESTERN/CENTRAL GULF COASTAL AREAS...INSTABILITY MAY NOT
SIGNIFICANTLY INCREASE. BUT...BOUNDARY LAYER WARMING/ MOISTENING
ACROSS UPPER TEXAS COASTAL AREAS INTO THE LOWER MISSISSIPPI VALLEY
MAY BECOME SUFFICIENT FOR THUNDERSTORM ACTIVITY ROOTED CLOSER TO THE
SURFACE. AND...DEEP LAYER SHEAR...AS WELL AS LOW-LEVEL
HODOGRAPHS...ARE EXPECTED TO BECOME INCREASINGLY FAVORABLE FOR
SUPERCELLS WITH THE RISK OF TORNADOES/DAMAGING WIND GUSTS...THOUGH
THE PRIMARY THREAT APPEARS AFTER THE END OF THIS FORECAST PERIOD.
.KERR.. 12/28/2007
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