SWODY2
SPC AC 121723
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1223 PM CDT THU APR 12 2007
VALID 131200Z - 141200Z
..THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NE AND ECNTRL
TX...FAR SE OK...SRN AR AND NRN LA...
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...ARKLATX REGION AND LOWER MS VALLEY...
..ARKLATX/LOWER MS VALLEY...
LATEST WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A WELL-DEFINED
UPPER-LEVEL TROUGH OVER THE SWRN STATES WITH AN UPPER-LOW LOCATED
OVER CNTRL CA AND WRN NV. THIS FEATURE WILL CONTINUE TO DIG SEWD
INTO AZ TONIGHT AND MOVE QUICKLY EWD INTO WEST TX FRIDAY. A
LOW-LEVEL JET AHEAD OF THE APPROACHING TROUGH WILL BRING WARM MOIST
AIR INTO EAST TX AND MODERATE INSTABILITY SHOULD DEVELOP ACROSS MOST
OF EAST TX BY FRIDAY AFTERNOON. THE GREATEST INSTABILITY SHOULD
EXIST SOUTH OF A WARM FRONT WHICH SHOULD BE LOCATED FROM NEAR
DALLAS/FORT WORTH EXTENDING EWD ACROSS FAR SRN AR. THUNDERSTORMS
SHOULD BE ONGOING IN NORTHWEST AND NCNTRL TX DURING THE MORNING
ASSOCIATED WITH THE LOW-LEVEL JET. THIS ACTIVITY SHOULD SPREAD EWD
AND EXPAND IN COVERAGE ACROSS NE TX AND SRN OK FRIDAY AFTERNOON. THE
GREATEST THUNDERSTORM COVERAGE SHOULD EXIST ALONG THE WARM FRONT
EXTENDING NWD FOR 100 MILES OR SO. THUNDERSTORMS SHOULD CONTINUE TO
EXPAND THROUGH THE EVENING HOURS WITH A LARGE MCS MOVING EWD ACROSS
AR/LA INTO WRN MS DURING THE OVERNIGHT PERIOD. THUNDERSTORM
DEVELOPMENT MAY ALSO OCCUR SWD ACROSS FAR EAST TX AS THE CAPPING
INVERSION WEAKENS OVERNIGHT.
THE GREATEST SEVERE THREAT SHOULD EXIST WITH THUNDERSTORMS THAT
DEVELOP IN A FAIRLY NARROW ZONE NEAR THE WARM FRONT FRIDAY AFTERNOON
AND EVENING. FORECAST SOUNDINGS ALONG AND JUST SOUTH OF THE WARM
FRONT LATE FRIDAY AFTERNOON SHOW IMPRESSIVE WIND SHEAR PROFILES WITH
0-6 KM SHEAR VALUES OF 60 KT SUGGESTING SUPERCELLS WILL BE LIKELY
UPON THUNDERSTORM INITIATION FRIDAY AFTERNOON. IN ADDITION...0-1 KM
SHEAR VALUES OF 25 TO 30 KT AND SUBSTANTIAL DIRECTIONAL TURNING
BELOW 850 MB SHOULD BE FAVORABLE FOR TORNADOES ESPECIALLY WITH
SUPERCELLS THAT DEVELOP NEAR THE WARM FRONTAL BOUNDARY. THE TORNADO
THREAT MAY BECOME ENHANCED WITH RIGHT MOVING SUPERCELLS THAT TRACK
EWD ALONG THE WARM FRONT. THE SYNOPTIC SETUP APPEARS SOMEWHAT
SIMILAR TO THE MARCH 28, 2000 FORT WORTH TX TORNADO EVENT ONLY THIS
SYSTEM AND THE WIND FIELDS FRIDAY WILL BE STRONGER. ALSO...THE MID
TO UPPER-LEVEL JET IS MORE CYCLONICALLY CURVED AND THE GREATEST
TORNADO THREAT AREA MAY BE SHIFTED SEWD COMPARED TO MARCH 28, 2000.
A FEW SIGNIFICANT TORNADOES ARE POSSIBLE ACROSS NE TX AND NW LA WITH
LONGER-LIVED SUPERCELLS ALSO POSSIBLE. LARGE HAIL AND WIND DAMAGE
WILL ALSO LIKELY ACCOMPANY SUPERCELLS THAT DEVELOP FRIDAY AFTERNOON
AND EVENING. ISOLATED VERY LARGE HAIL COULD OCCUR WITH SUPERCELLS
ALONG THE WRN EDGE OF THE INSTABILITY AXIS IN NCNTRL TX DUE TO
STEEPER MID-LEVEL LAPSE RATES THERE. HOW FAR SOUTH THE SEVERE THREAT
WILL EXIST STILL REMAINS HIGHLY UNCERTAIN AND THE STRENGTH OF THE
CAPPING INVERSION WILL LIKELY DETERMINE SEVERE WEATHER REPORT
COVERAGE ACROSS ECNTRL TX. AS A LARGE MCS DEVELOPS FRIDAY
EVENING...THE SEVERE THREAT SHOULD CONTINUE SPREADING EWD ACROSS SRN
AR AND LA WITH THE THREAT DIMINISHING LATE FRIDAY NIGHT ACROSS CNTRL
MS.
..ERN TX PANHANDLE/SW OK...
AN UPPER-LOW EVIDENT ON WATER VAPOR IMAGERY WILL MOVE SEWD INTO AZ
TONIGHT AND EWD TO THE VICINITY OF THE TX PANHANDLE FRIDAY
AFTERNOON. THUNDERSTORM DEVELOPMENT NEAR AND SOUTHEAST OF THE
UPPER-LOW SHOULD OCCUR AS SFC TEMPS WARM LATE FRIDAY MORNING INTO
THE AFTERNOON. FORECAST SOUNDINGS NEAR THE UPPER-LOW FRIDAY
AFTERNOON SHOW VERTICAL SHEAR PROFILES SUFFICIENT FOR SUPERCELLS.
IN ADDITION...LAPSE RATES WILL BE VERY STEEP AND SEVERE
THUNDERSTORMS WITH LARGE HAIL APPEAR LIKELY. THE SEVERE THREAT
SHOULD SPREAD EWD FROM THE TX PANHANDLE INTO SW OK AND NCNTRL TX BY
LATE AFTERNOON AND EARLY EVENING. A FEW DAMAGING WIND GUSTS AND AN
ISOLATED TORNADO THREAT MAY ALSO OCCUR WITH THE STRONGER SUPERCELL
THUNDERSTORMS.
.BROYLES.. 04/12/2007
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