MESOSCALE DISCUSSION 1200
   NWS STORM PREDICTION CENTER NORMAN OK
   0641 AM CDT THU JUN 18 2009
   
   AREAS AFFECTED...SD...NE...IA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 458...
   
   VALID 181141Z - 181315Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 458
   CONTINUES.
   
   RECENT TRENDS SUGGEST A SLIGHT DECLINE IN CONVECTIVE INTENSITY
   WITHIN COMPACT MCS/BOW MOVING GENERALLY EWD AT 50KT INTO NWRN IA
   ATTM. SYSTEM MAY BE STRUGGLING TO OVERCOME STRONG CONVECTIVE
   INHIBITION EXHIBITED IN LATEST RUC MODEL SOUNDINGS FROM THE REGION. 
   HOWEVER...LARGER SCALE SUPPORT IN THE FORM OF A LOW-AMPLITUDE SHORT
   WAVE TROUGH...AND ABUNDANT WARM/MOIST AIR STREAMING INTO THE AREA
   ALONG THE EDGE OF PLAINS CAPPING INVERSION...SHOULD CONTINUE TO
   MAINTAIN SOME FORM OF THE COMPLEX ACROSS NRN IA OVER THE NEXT COUPLE
   OF HOURS. AT ITS CURRENT SPEED...THE LEADING EDGE OF STRONG
   CONVECTION WILL REACH THE ERN EDGE OF SVR WATCH 458 IN ABOUT ONE
   HOUR. A NEW WATCH IS POSSIBLE DOWNSTREAM ACROSS NRN AND CNTRL IA
   UNLESS THE MCS CONTINUES TO SHOW A STEADY DECLINE IN STRENGTH.
   
   ..CARBIN.. 06/18/2009
   
   
   ATTN...WFO...DVN...ARX...DMX...FSD...OAX...
   
   LAT...LON   43489699 43419460 43339256 43129193 42459178 41949304
               42029439 42069557 42189691 43489699