MESOSCALE DISCUSSION 1743
   NWS STORM PREDICTION CENTER NORMAN OK
   0614 PM CDT TUE JUL 20 2004
   
   AREAS AFFECTED...SERN SD THROUGH NERN NEB
   
   CONCERNING...TORNADO WATCH 657...
   
   VALID 202314Z - 210115Z
   
   CORRECTED FOR TYPE OF BOX REFERENCE
   
   THREAT FOR LARGE HAIL...MICROBURSTS AND POSSIBLY ISOLATED TORNADOES
   EXPECTED TO PERSIST ANOTHER FEW HOURS.
   
   EARLY THIS EVENING SCATTERED STORMS THAT DEVELOPED ALONG A SURFACE
   BOUNDARY FROM SERN SD SWD THROUGH NERN NEB CONTINUE SLOWLY EAST.
   MANY OF THE STORMS HAVE...SO FAR...NOT BEEN VERY PERSISTENT...MOST
   LIKELY DUE TO MARGINAL CLOUD LAYER SHEAR WHICH IS PROMOTING OUTFLOW
   DOMINANCE. DOWNSTREAM FROM THIS ACTIVITY...THE ATMOSPHERE REMAINS
   STRONGLY UNSTABLE WITH MLCAPE AROUND 3500 J/KG ALONG WITH A MOIST
   BOUNDARY LAYER...LOWER LCLS AND STRONGER LOW LEVEL SHEAR. HOWEVER...
   OBJECTIVE ANALYSIS DATA ALSO SHOW A STRONGER CAP ACROSS FAR SERN SD
   AND EXTREME NE NEB. GIVEN THE SLOW STORM MOTIONS...IT REMAINS
   QUESTIONABLE WHETHER THE STORMS WILL SURVIVE INTO THE MORE FAVORABLE
   ENVIRONMENT BEFORE THE ONSET OF NOCTURNAL COOLING FURTHER
   STRENGTHENS THE CAP.
   
   ..DIAL.. 07/20/2004
   
   
   ATTN...WFO...LOT...MKX...DVN...ARX...
   
   41558815 41229061 42389138 43219000 42818819