SWODY1
SPC AC 171629
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT TUE APR 17 2007
VALID 171630Z - 181200Z
..THERE IS A SLGT RISK OF SVR TSTMS NORTHWEST AND NORTH CENTRAL
TX...
..TX...
STRONG UPPER LOW IS TRACKING EASTWARD THIS MORNING ACROSS NM INTO
WEST TX. THIS FEATURE IS FORECAST TO BE OVER WESTERN MS BY WED
MORNING. STRONG SOUTHERLY LOW LEVEL WINDS AHEAD OF SYSTEM WILL
TRANSPORT AIR MASS CURRENTLY OVER THE MID TX GULF COAST REGION
NORTHWARD INTO WESTERN NORTH TX THIS AFTERNOON. HOWEVER...THIS AIR
MASS IS ONLY MARGINALLY MOIST/UNSTABLE DUE TO RECENT INTRUSION OF
COLD AIR. SURFACE DEWPOINTS IN THE 50S TO NEAR 60F ARE POSSIBLE AS
FAR NORTHWEST AS SPS/ABI THIS AFTERNOON.
VISIBLE SATELLITE IMAGERY SHOWS RAPID CLEARING OCCURRING OVER PARTS
OF WEST TX...BENEATH STEEP MID LEVEL LAPSE RATES. THIS WILL HELP
DRYLINE MIX EASTWARD IN WEST-CENTRAL TX BY MID AFTERNOON. MORNING
OBSERVED AND RECENT AMDAR SOUNDING DATA SUGGEST A PRONOUNCED CAPPING
INVERSION WILL SUPPRESS DEEP CONVECTION THROUGH MUCH OF THE DAY.
HOWEVER...ALL MODEL GUIDANCE INDICATES THAT STRENGTHENING FORCING
FOR ASCENT WILL HELP ERODE CAP AND LEAD TO SCATTERED THUNDERSTORMS
AFTER 18Z.
INITIAL STORMS MAY FORM IN POST-DRYLINE AIR MASS OVER WEST TX.
THESE HIGH-BASED STORMS WILL LIKELY BUILD EASTWARD INTO MORE MOIST
LOW LEVEL AIR MASS AND INTENSIFY FROM SOUTHEAST OF CDS TO NEAR SJT.
ACTIVITY WILL THEN DEVELOP SOUTHEASTWARD DURING THE AFTERNOON AND
EVENING ACROSS OUTLOOK AREA. COLD TEMPERATURES ALOFT AND STEEP
LAPSE RATES WILL PROMOTE A RISK OF LARGE HAIL. ALSO...DEEP LAYER
SHEAR WILL BE SUPPORTIVE OF ORGANIZED MULTICELL OR OCCASIONAL
SUPERCELL STORMS CAPABLE OF DAMAGING WINDS. ISOLATED TORNADOES
CANNOT BE RULED OUT...BUT OVERALL RISK APPEARS RATHER MINIMAL DUE TO
LIMITED MOISTURE...AND EXTENSIVE CLOUD COVER OVER NORTHWEST TX WHERE
NEAR-SURFACE AMBIENT VORTICITY IS FORECAST.
.HART/GUYER.. 04/17/2007
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