MESOSCALE DISCUSSION 1403
   NWS STORM PREDICTION CENTER NORMAN OK
   0309 PM CDT SUN JUN 26 2011
   
   AREAS AFFECTED...PORTIONS SERN NEB...SWRN IA...NWRN CORNER MO.
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 262009Z - 262215Z
   
   CONDITIONAL BUT POTENTIALLY SIGNIFICANT SVR THREAT EXISTS ACROSS
   DISCUSSION AREA INITIALLY INVOLVING SUPERCELLS...AS ENVIRONMENT
   APPEARS TO BE GETTING MORE FAVORABLE INVOF EXISTING CONVECTION AND
   AHEAD OF NRN NEB MCS.  WW MAY BE REQUIRED WITHIN NEXT HOUR OR TWO.
   
   INITIAL SFC WARM FRONT IS STILL DRAWN S OF AREA...FROM LOW NEAR DDC
   NEWD ACROSS HLC AREA THEN ARCHING TO BETWEEN SLN-CNK AND SEWD OVER
   SERN KS.  VERY HOT/WELL-MIXED AIR MASS WILL CONTINUE TO ITS S. 
   SECONDARY WARM-FRONTAL ZONE IS DEVELOPING INVOF KS/NEB BORDER AND
   WILL MOVE NWD ACROSS SRN NEB...AND IS EVIDENT BOTH IN SFC OBS AND IN
   PRONOUNCED CHANGE IN LOW-CLOUD CHARACTER PER VIS IMAGERY. 
   DIFFERENTIAL HEATING...AS WELL AS RAIN-COOLED AIR FROM CONVECTION TO
   ITS N OVER SERN NEB...MAY REINFORCE THIS BAROCLINIC ZONE.
   
   NON-SVR ELEVATED TSTMS HAVE BEEN DEVELOPING AND MOVING EWD ACROSS
   SERN NEB BETWEEN OMA-GRI...WITHIN BAND OF MIDLEVEL ASCENT AND NEAR
   ZONE OF RELATIVELY MAXIMIZED 700-MB MOISTURE.  LOW-LEVEL AIR MASS IN
   THIS AREA IS EXPECTED TO DESTABILIZE FROM S-N AS NRN WARM-FRONTAL
   SEGMENT APCHS...LEADING TO STG SFC HEATING OF AIR MASS CONTAINING
   LOW-MID 70S F SFC DEW POINTS.  THIS WILL BOOST MLCAPE TO 4000-5000
   J/KG RANGE...JUXTAPOSED WITH NEAR-FRONTAL MAXIMA IN LOW-LEVEL
   VORTICITY AND HODOGRAPH SIZE.  BACKED SFC WINDS WILL CONTRIBUTE BOTH
   TO EFFECTIVE SRH 200-400 J/KG AND EFFECTIVE SHEAR MAGNITUDES 50-60
   KT.  EXISTING CONVECTION MAY BECOME SFC-BASED AND SVR AS MORE
   FAVORABLE AIR MASS BUILDS INTO ITS VICNITY...AND/OR NEW DEVELOPMENT
   MAY OCCUR ALONG WARM FRONT...AND/OR NRN NEB MCS ENTERS NRN PARTS OF
   AREA.  HOWEVER...THREAT FOR NEW TSTMS IS CONDITIONAL GIVEN 18Z OAX
   RAOB SHOWING CAPPING THAT ACTUALLY STRENGTHENED SINCE 12Z.  ANY
   SUSTAINED/SFC-BASED TSTM IN NEAR-FRONTAL ENVIRONMENT OFFERS RISK OF
   VERY LARGE/DAMAGING HAIL...SVR GUSTS AND TORNADOES.
   
   ..EDWARDS.. 06/26/2011
   
   
   ATTN...WFO...DMX...EAX...OAX...GID...
   
   LAT...LON   42069799 41879649 41429559 41199516 40819504 40409535
               40399718 40539882 40749898 42069799