MESOSCALE DISCUSSION 1290
   NWS STORM PREDICTION CENTER NORMAN OK
   0321 PM CDT TUE JUN 23 2009
   
   AREAS AFFECTED...ERN NEB..SRN IA
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 232021Z - 232115Z
   
   STORMS HAVE DEVELOPED ALONG OUTFLOW BNDRY TO THE NORTH OF OMA...AND
   ADDITIONAL STORMS MAY FORM ALONG THE BNDRY FROM CENTRAL IA WSWWD
   INTO ERN NEB.  GIVEN EXTREME INSTABILITY OF ENVIRONMENT...A NEW WW
   WILL BE ISSUED OVER THE AREA.
   
   LINEAR CONVECTIVE SYSTEM CONTINUES TO MOVE EWD ACROSS CENTRAL
   IA...WITH NEW STORMS DEVELOPING ALONG THE SRN END OF THE LINE NEAR
   THE SRN EDGE OF WW 498.  IN ADDITION...SEVERAL NEW STORMS HAVE
   DEVELOPED WWD ALONG THE OUTFLOW BNDRY EXTENDING INTO EXTREME ERN NEB
   AND FURTHER DEVELOPMENT WWD ALONG THE BNDRY IS POSSIBLE.
   
   WITH SURFACE TEMPERATURES IN THE 90S AND DEW POINTS IN THE UPPER
   70S/NEAR 80...EXTREMELY UNSTABLE ENVIRONMENT IS PRESENT AS INDICATED
   BY 18Z OAX SOUNDING WITH MLCAPE TO 3800 J/KG.  LIMITING PARAMETER
   FOR MORE WIDESPREAD SEVERE THREAT IS RELATIVELY WEAK FLOW ALOFT AND
   WEAK VERTICAL SHEAR OVER SRN IA AND SERN NEB.  HOWEVER...MAGNITUDE
   OF INSTABILITY INDICATES POTENTIAL FOR LARGE HAIL AND DAMAGING
   DOWNBURST WINDS.  NEW WW WILL BE ISSUED SOON ACROSS THE DISCUSSION
   AREA.
   
   ..WEISS.. 06/23/2009
   
   
   ATTN...WFO...DVN...DMX...EAX...OAX...GID...
   
   LAT...LON   41389826 41579690 41889589 41919455 41869293 41899232
               42359199 42539159 42509098 41969068 41219101 40879128
               40819243 40699484 40359742 40509843 41389826