SPC MESOSCALE DISCUSSION 0659 FOR CENTRAL TX
CONCERNING...SEVERE THUNDERSTORM WATCH 197...

VALID 052217Z - 060000Z

MOST ORGANIZED/INTENSE ACTIVITY EXTENDS ALONG THE I-35 CORRIDOR
FROM HILL TO CORYELL COUNTY ATTM...WHICH IS MAINTAINING A ENEWD
MOTION OF 25 KT.  SECOND AREA OF CONVECTION IS ORIENTED SW-NE AND
APPEARS TO BE ROOTED A BIT LESS IN THE BOUNDARY LAYER WITH A SLOW
NWD MOTION.

SEVERE PARAMETERS REMAIN FAVORABLE ACROSS THE WW WITH MEAN-MIXED
CAPES IN EXCESS OF 2000 J/KG AND DEEP LAYER SHEAR AT GRK OF 45 KT
/BRN-SHEAR OF 51 M2/S2.  GIVEN THE INSTABILITY AXIS AND SUBTLE
INSTABILITY GRADIENT EXTENDING ENEWD INTO NERN TX...ACTIVITY MAY
CONTINUE PRODUCING ISOLATED HAIL/WIND NEAR SEVERE LEVELS FOR A FEW
MORE HOURS.  AN ISOLATED SUPERCELL WILL ALSO REMAIN POSSIBLE. 
GIVEN THE MORE WIDESPREAD DEVELOPMENT OF WEAKLY ORGANIZED STORMS
MOVING NWD...NEW WW INTO NERN TX NOT EXPECTED ATTM.

LATEST SURFACE ANALYSIS/VSBL IMAGERY INDICATES OUTFLOW BOUNDARY
REMAINS WELL DEFINED FROM BELL INTO MENARD COUNTY...WHICH IS
LIMITING INSTABILITY INTO NWRN PARTS OF WW.  HOWEVER...DRY LINE IS
ALSO WELL DEFINED JUST WEST OF WW AND ACTIVITY MAY DEVELOP WITHIN
STRONG INSTABILITY OVER THE HILL COUNTRY/EDWARDS PLATEAU REGION
OVER THE NEXT FEW HOURS.

..EVANS.. 05/05/01