MESOSCALE DISCUSSION 1341
   NWS STORM PREDICTION CENTER NORMAN OK
   0914 PM CDT SUN JUL 07 2013

   AREAS AFFECTED...PORTIONS NEB...WRN SD...NWRN IA...EXTREME SERN SD.

   CONCERNING...SEVERE THUNDERSTORM WATCH 397...

   VALID 080214Z - 080415Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 397
   CONTINUES.

   SUMMARY...BKN/WAVY BAND OF TSTMS HAS DEVELOPED FROM SRN MN SWWD
   ACROSS NERN AND CENTRAL NEB.  SVR THREAT WITH THIS ACTIVITY SHOULD
   PERSIST THROUGH AT LEAST 05Z AND MAY SHIFT SE OF CURRENT WW BOUNDS
   INTO PORTIONS WRN IA AND SERN NEB.  THOSE AREAS WILL BE MONITORED
   FOR ANOTHER WW.  MEANWHILE...HAIL/WIND THREATS WILL BE LOCALLY
   MAXIMIZED WHERE CONVECTIVE MODE TRENDS TOWARD RELATIVELY DISCRETE
   SUPERCELLS AND BOW ECHOES...RESPECTIVELY.  MEANWHILE...BAND OF SVR
   TSTMS OVER SERN MT AND NWRN WY MAY PRODUCE ISOLATED SVR/DAMAGING
   GUSTS OVER WRN SD BEFORE MOVING INTO MORE STABLE AIR AND WEAKENING.

   DISCUSSION...FAVORABLY UNSTABLE BOUNDARY-LAYER AIR OVER THIS REGION
   IS BECOMING FRAGMENTED BY OUTFLOW ARC FROM SERN SD/NRN NEB
   CONVECTION.  MESOANALYSIS AT 02Z SHOWED OUTFLOW BOUNDARY FROM LYON
   COUNTY IA TO ANTELOPE COUNTY NEB...SRN SANDHILLS AROUND HOOKER
   COUNTY NEB...THEN NWWD INTO SRN BLACK HILLS.  BOUNDARY WILL CONTINUE
   TO MOVE SWD OUT OF SANDHILLS AND SEWD OVER NERN NEB...MERGING WITH
   AND POTENTIALLY UNDERCUTTING ONGOING CONVECTION OVER LBF AREA IN
   NEXT COUPLE OF HOURS.  OUTFLOW FROM EARLIER CONVECTION OVER KS ALSO
   WAS EVIDENT IN REFLECTIVITY ANIMATIONS...MOVING NWD THROUGH SRN TIER
   OF NEB COUNTIES SW-SE OF HSI.  RELATED STABILIZATION JUXTAPOSED WITH
   NOCTURNAL DIABATIC COOLING SHOULD LIMIT SRN EXTENT OF SVR THREAT TO
   THOSE COUNTIES THAT HAVE BEEN ADDED TO WW -- FROM GOSPER-ADAMS
   CORRIDOR NWD.  MEANWHILE...FARTHER E...CORRIDOR OF FAVORABLY
   MOIST/UNSTABLE AIR REMAINS PARALLEL TO AND AHEAD OF BOUNDARY...FROM
   NWRN/W-CENTRAL IA SWWD OVER PORTIONS SERN/S-CENTRAL NEB.  WHILE DEEP
   SHEAR WEAKENS SEWD...AND SFC COOLING WILL INCREASE MLCINH WITH
   TIME...LATTER PROCESS WILL BE GRADUAL GIVEN RICH BOUNDARY-LAYER
   MOISTURE EVIDENT IN UPPER 60S TO LOW 70S F DEW POINTS.  AS
   SUCH...SVR WIND THREAT MAY EXTEND SLIGHTLY SE OF EXISTING WW...WITH
   FORCED ASCENT MAINTAINING SOME CONVECTION INTO AREAS OF MODEST
   MLCINH.  EITHER ADDITIONAL COUNTIES OR NEW WW MAY BE NEEDED.

   ..EDWARDS.. 07/08/2013


   ATTN...WFO...DMX...FSD...OAX...GID...LBF...UNR...GLD...BOU...
   CYS...

   LAT...LON   41290131 41779931 42839728 43599605 43339350 42079349
               40649580 40099804 40340096 41280259 43020285 43030403
               45930390 45870288 44170195 43170199 41830141 41290131