SWODY1
SPC AC 131621
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CDT FRI APR 13 2007
VALID 131630Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
PARTS OF EAST TX...NORTHERN LA...AND SOUTHWEST AR...
..THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SOUTHERN
PLAINS AND LOWER MS VALLEY...
POWERFUL UPPER TROUGH NOW SHOWN BY WATER VAPOR IMAGERY OVER SOUTHERN
NM WILL TRACK EASTWARD ACROSS TX TONIGHT. AHEAD OF THE
SYSTEM...STRONG SOUTHERLY LOW LEVEL WINDS ARE TRANSPORTING RICH GULF
MOISTURE NORTHWARD ACROSS PARTS OF TX/LA. PRESENT INDICATIONS ARE
FOR AN ACTIVE SEVERE WEATHER EVENT ACROSS PARTS OF NORTHERN TX INTO
NORTHERN LA THIS AFTERNOON THROUGH TONIGHT...WITH A RISK OF A FEW
STRONG TORNADOES...VERY LARGE HAIL...AND DAMAGING WINDS.
CURRENT SURFACE ANALYSIS SHOWS MAIN LOW NORTH OF MAF...WITH WARM
FRONT EXTENDING EAST-SOUTHEASTWARD TO NEAR ACT. THIS BOUNDARY WILL
LIFT NORTHWARD THROUGH THE DAY WITH MID/UPPER 60S DEWPOINTS
SPREADING INTO MUCH OF NORTH-CENTRAL AND EAST TX. MORNING OBSERVED
AND FORECAST SOUNDINGS OVER THIS REGION SHOW STEEP MID LEVEL LAPSE
RATES...FAVORABLE FOR THE DEVELOPMENT OF MODERATE INSTABILITY BY
LATE THIS AFTERNOON. SOUNDINGS ALSO SHOW RATHER WARM TEMPERATURES
AT 700MB...SUGGESTING THAT CAPPING INVERSION WILL INHIBIT WARM
SECTOR CONVECTION UNTIL LATER THIS AFTERNOON.
STRONG WARM ADVECTION AND STRENGTHENING LOW LEVEL JET WILL HELP TO
MAINTAIN A RISK OF SCATTERED STORMS ALONG AND NORTH OF WARM FRONT
FROM NORTHWEST TX...ACROSS SOUTHERN OK...INTO SOUTHERN AR. THERE IS
A NARROW ZONE ALONG THE WARM FRONT OVER NORTHWEST TX WHERE STORMS
COULD BECOME SURFACE-BASED WITH A RISK OF ISOLATED TORNADOES.
OTHERWISE...LARGE HAIL WILL BE THE MAIN THREAT.
LATER THIS AFTERNOON...SUFFICIENT HEATING ALONG THE DRYLINE COMBINED
WITH APPROACHING UPPER TROUGH WILL LIKELY RESULT IN SCATTERED
THUNDERSTORMS WEST/SOUTHWEST OF THE DFW AREA. OTHER ISOLATED CELLS
MAY DEVELOP WITHIN THE WARM SECTOR WHERE LOW LEVEL WARM ADVECTION
WILL BE OCCURRING. VERTICAL SHEAR PROFILES THROUGHOUT THIS REGION
WILL BE FAVORABLE FOR SUPERCELLS. LOW LEVEL SHEAR AND MOISTURE
PROFILES WILL ALSO BE QUITE FAVORABLE FOR TORNADOES /PERHAPS STRONG/
AS STORMS SPREAD EASTWARD ACROSS NORTHEAST TX AND INTO LA DURING THE
EVENING/NIGHT. DAMAGING WINDS AND HAIL WILL ALSO BE POSSIBLE ACROSS
THE MDT RISK AREA.
OVERNIGHT...STORMS MAY BECOME MORE LINEARLY FORCED AS UPPER TROUGH
SPREADS EASTWARD. THIS WILL INCREASE THE RISK OF DAMAGING WINDS AS
FAR EAST AS EASTERN LA AND WESTERN MS.
.HART/JEWELL.. 04/13/2007
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