SWODY1
SPC AC 140058
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 PM CDT FRI APR 13 2007
VALID 140100Z - 141200Z
..THERE IS A HIGH RISK OF SVR TSTMS FROM A PORTION OF NERN TX INTO
NWRN AND W CNTRL LA...
..THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF CNTRL AND ERN TX
INTO LA...
..THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE ERN HALF OF
TX...SERN OK THROUGH THE LOWER MS VALLEY...
..S CNTRL THROUGH NERN TX...SERN OK AND THE LOWER MS VALLEY...
A COLD FRONT EXTENDS FROM N CNTRL TX SWWD THROUGH CNTRL TX AND
FARTHER SW TO NEAR DEL RIO. A WARM FRONT EXTENDS EWD THROUGH NERN
TX...NRN LA AND CNTRL MS. BOUNDARY LAYER DEWPOINTS IN THE UPPER 60S
HAVE ADVECTED AS FAR N AS CNTRL AND E CNTRL TX INTO CNTRL LA BENEATH
STEEP 700-500 MB LAPSE RATES. THIS HAS RESULTED IN MLCAPE FROM 2500
J/KG OVER S CNTRL TX TO NEAR 1000 J/KG OVER ERN TX THROUGH CNTRL AND
SRN LA DESPITE WIDESPREAD LOW CLOUDS IN THAT AREA. N OF WARM FRONT
THROUGH ERN OK AND AR...INSTABILITY REMAINS ELEVATED WITH MUCAPE
FROM 1000 TO 2500 J/KG.
LOW LEVEL JET WILL STRENGTHEN OVER ERN TX AND THE LOWER MS VALLEY
THIS EVENING DOWNSTREAM FROM ERN ADVANCING UPPER TROUGH. THIS WILL
MAINTAIN INFLUX OF UPPER 60S DEWPOINTS THROUGH ERN TX AND THE LOWER
MS VALLEY AND PROMOTE A SLOW NWD RETREAT OF THE WARM FRONT. STORMS
CONTINUE DEVELOPING ALONG EWD ADVANCING COLD FRONT FROM NERN TX SWWD
TO JUST NE OF DEL RIO. STORMS WITHIN THE LINE CONTAIN MIXED MODES
WITH BOTH SUPERCELL STRUCTURES AND LINE SEGMENTS. SUPERCELL THAT
PRODUCED A TORNADO EARLIER IN THE DALLAS/FORT WORTH AREA REMAINS
INTENSE AND IS MOVING INTO NERN TX. DAMAGING WIND...VERY LARGE HAIL
AND A FEW TORNADOES WILL REMAIN POSSIBLE WITH STORMS WITHIN THE LINE
AS IT ADVANCES EWD THROUGH TX THIS EVENING.
FARTHER EAST...OTHER STORMS ARE DEVELOPING ALONG WARM CONVEYOR BELT
WITHIN ZONE OF WARM ADVECTION AND ISENTROPIC ASCENT ASSOCIATED WITH
THE LOW LEVEL JET FROM SERN TX THROUGH WRN LA AND FARTHER NWD INTO
AR. STORMS IN AR ARE ELEVATED N OF THE WARM FRONT. HOWEVER...THE 00Z
SHREVEPORT RAOB SHOWS 8C/KM MID LEVEL LAPSE RATES...SUBSTANTIAL
MUCAPE AND CLOUD LAYER SHEAR SUFFICIENT FOR ROTATING UPDRAFTS. LARGE
HAIL WILL BE THE MAIN THREAT WITH THIS ACTIVITY. FARTHER S ALONG THE
WARM CONVEYOR BELT...STORMS ARE EXPECTED TO GRADUALLY INTENSIFY AS
THE BOUNDARY LAYER MOISTENS AND DESTABILIZES NWD. FORECAST SOUNDINGS
SHOW LARGE LOW LEVEL HODOGRAPHS AND STORM RELATIVE HELICITY IN
VICINITY OF THE LOW LEVEL JET WITH EFFECTIVE INFLOW LAYER BASES NEAR
THE SURFACE WHERE DEWPOINTS ARE IN THE UPPER 60S. POTENTIAL WILL
EXIST FOR A FEW SUPERCELLS CAPABLE OF PRODUCING STRONG TORNADOES
WITH THIS ACTIVITY THIS EVENING AND INTO THE OVERNIGHT. HAVE SHIFTED
THE HIGH RISK A LITTLE FARTHER EAST INTO LA TO ACCOUNT FOR THIS
POSSIBILITY.
.DIAL.. 04/14/2007
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