SWODY1
SPC AC 130557
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT FRI APR 13 2007
VALID 131200Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF CNTRL THROUGH NERN
TX INTO THE LOWER MS VALLEY...
..THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS INTO THE
LOWER MS VALLEY...
..SYNOPSIS...
SHORTWAVE TROUGH CURRENTLY OVER THE SWRN U.S. WILL ADVANCE EAST INTO
THE SRN PLAINS FRIDAY AFTERNOON. ATTENDANT LEE SURFACE LOW AND COLD
FRONT WILL SHIFT EAST THROUGH TX WHILE WARM FRONT LIFTS NWD TO NEAR
THE RED RIVER AREA BY EARLY FRIDAY EVENING.
..CNTRL AND ERN TX THROUGH LOWER MS VALLEY...
LATEST OBSERVATIONS AND THE 00Z RAOB DATA SHOW RICH BOUNDARY LAYER
MOISTURE OVER S TX WITH DEWPOINTS AROUND 70. STRONG SLY LOW LEVEL
JET WILL PERSIST IN ADVANCE OF THE APPROACHING SHORTWAVE TROUGH AND
CONTRIBUTE TO THETA-E ADVECTION THROUGH CNTRL AND ERN TX FRIDAY IN
WAKE OF RETREATING WARM FRONT. SOME LOW CLOUDS MAY ACCOMPANY THE
INITIAL MOISTURE SURGE. HOWEVER...UPPER 60S DEWPOINTS RETURNING NWD
BENEATH STEEP MID LEVEL LAPSE RATES SHOULD CONTRIBUTE TO MODERATE
INSTABILITY WITH MLCAPE FROM 1500 TO 2000 J/KG. STORMS WILL LIKELY
BE ONGOING EARLY FRIDAY...MOSTLY WITHIN ZONE OF WARM ADVECTION AND
ISENTROPIC LIFT N OF WARM FRONT FROM PARTS OF N TX INTO OK AND KS.
THIS ACTIVITY SHOULD BE ELEVATED WITH A THREAT FOR MAINLY HAIL.
STORMS SHOULD GRADUALLY DEVELOP SWD INTO THE PRE-FRONTAL WARM SECTOR
ALONG WARM CONVEYOR BELT AS THE ATMOSPHERE DESTABILIZES AND AS UPPER
DIVERGENCE AND FORCING FOR ASCENT INCREASES WITH THE APPROACH OF THE
UPPER TROUGH. A STRONG 50+ KT LOW LEVEL JET WILL PERSIST OVER CNTRL
AND ERN TX WITHIN EXIT REGION OF CYCLONICALLY CURVED UPPER JET. THIS
WILL RESULT IN FAVORABLE LOW LEVEL HODOGRAPHS AND DEEP LAYER SHEAR
FOR ORGANIZED STORM STRUCTURES INCLUDING SUPERCELLS AND BOW ECHOES
CAPABLE OF PRODUCING A FEW TORNADOES...VERY LARGE HAIL AND DAMAGING
WIND. GIVEN THE EXPECTED COMBINATION OF LOW-MID LEVEL SHEAR AND CAPE
ISOLATED STRONG TORNADOES WILL BE POSSIBLE...ESPECIALLY WITH ANY
DISCRETE SUPERCELL MODES. ACTIVITY WILL SHIFT EAST INTO THE LOWER MS
VALLEY FRIDAY EVENING WITH A CONTINUED SEVERE THREAT.
..NWRN TX INTO SWRN OK...
MUCH OF THE STORMS IN OK ARE EXPECTED TO REMAIN ELEVATED N OF WARM
FRONT WITH A THREAT FOR MAINLY HAIL. HOWEVER...MODELS SUGGEST MID
LEVEL DRY SLOT COULD ADVANCE NEWD INTO NWRN TX AND PARTS OF SWRN OK
DURING THE AFTERNOON...AND THIS WILL INCREASE THE CHANCES FOR LOW
CLOUDS TO MIX OUT. IF LOW CLOUDS CAN MIX OUT...SURFACE HEATING AND
COLD MID LEVEL PROFILES SHOULD RESULT IN AT LEAST MARGINAL SURFACE
BASED INSTABILITY IN A RELATIVELY NARROW CORRIDOR. ADDITIONAL STORMS
MAY DEVELOP WITHIN ZONE OF DPVA NEAR TRIPLE POINT OR SWD ALONG COLD
FRONT AND ADVANCE EAST. A CONDITIONAL THREAT WILL EXIST FOR DAMAGING
WIND...LARGE HAIL AND POSSIBLY AN ISOLATED TORNADO OR TWO.
.DIAL/CROSBY.. 04/13/2007
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