MESOSCALE DISCUSSION 2091
   NWS STORM PREDICTION CENTER NORMAN OK
   0753 PM CDT MON AUG 23 2004
   
   AREAS AFFECTED...CNTRL AND SRN SD THROUGH WRN AND CNTRL
   NEB...EXTREME NE CO AND NW KS
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 776...
   
   VALID 240053Z - 240230Z
   
   THREAT FOR MAINLY LARGE HAIL AND ISOLATED DAMAGING WIND EXPECTED TO
   PERSIST FROM S CNTRL SD SWD THOUGH CNTRL AND SW NEB NEXT 2-3 HOURS.
   AREAS E OF WW 776 ACROSS E CNTRL NEB ARE ALSO BEING MONITORED FOR
   ADDITIONAL THUNDERSTORM DEVELOPMENT. 
   
   THIS EVENING A DRYLINE EXTENDS FROM CNTRL NEB SWWD TO A WEAK SURFACE
   LOW IN SWRN NEB. E OF THIS BOUNDARY...THE ATMOSPHERE REMAINS VERY
   UNSTABLE WITH MLCAPE FROM 2500 TO 3000 J/KG. GIVEN THE DEGREE OF
   INSTABILITY...SHEAR PROFILES REMAIN SUFFICIENT FOR SUPERCELLS ALONG
   AND E OF THE DRYLINE WITH AROUND 30 KT OF 0-6 KM SHEAR. STRONGEST
   STORMS REMAIN OVER TRIPP COUNTY IN SRN SD AND CUSTER COUNTY IN NEB
   AS OF 0035Z. HOWEVER...WEAK MID LEVEL FLOW IS RESULTING IN VERY SLOW
   STORM MOTIONS WITH SOME SWD PROPAGATION WHICH IS ALSO ENHANCING LOW
   LEVEL STORM RELATIVE HELICITY.
   
   OTHER STORMS ARE DEVELOPING A LITTLE FARTHER WEST IN W CNTRL NEB
   WHERE NUMEROUS OUTFLOW MERGERS ARE OCCURRING. SEVERE THREAT IS MORE
   MARGINAL IN THIS AREA DUE TO MORE LIMITED LOW LEVEL MOISTURE.
   HOWEVER...STORMS MAY INTENSIFY BRIEFLY AS THEY DEVELOP IN THE
   ENHANCED CONVERGENCE ZONE ASSOCIATED WITH MERGING OUTFLOWS. 
   
   OUTFLOW BOUNDARY OVER CNTRL NEB IS SURGING RAPIDLY EWD. THIS MIGHT
   PROMOTE ADDITIONAL STORMS DEVELOPING E OF WW 776 THIS EVENING AS IT
   INTERCEPTS THE STRONGER INSTABILITY E OF THE DRYLINE.
   
   ..DIAL.. 08/24/2004
   
   
   ATTN...WFO...FSD...ABR...GID...LBF...UNR...GLD...
   
   41999971 40310029 40030144 41230159 44210030 44529878