MESOSCALE DISCUSSION 1273
   NWS STORM PREDICTION CENTER NORMAN OK
   0539 AM CDT SAT JUN 18 2011
   
   AREAS AFFECTED...CNTRL AND ERN MO...SRN AND CNTRL IL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 498...
   
   VALID 181039Z - 181145Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 498
   CONTINUES.
   
   A WIND DAMAGE THREAT CURRENTLY ASSOCIATED WITH A BOWING LINE-SEGMENT
   IN ERN MO WILL MOVE EWD INTO SRN IL OVER THE NEXT FEW HOURS. THE
   THREAT SHOULD BECOME MORE ISOLATED WITH TIME BUT A LOCAL EXTENSION
   OR SMALL WW ISSUANCE CAN NOT BE RULED OUT.
   
   A WELL-DEVELOPED BOWING LINE-SEGMENT CURRENTLY IN ERN MO WILL
   CONTINUE TO MOVE ESEWD DOWN A GRADIENT OF MODERATE INSTABILITY INTO
   SRN IL. CONSIDERING THE FORWARD SPEED OF THE BOW IS ESTIMATED
   BETWEEN 40 AND 45 KT AND MODERATE INSTABILITY IS LOCATED AHEAD OF
   THE BOW...A WIND DAMAGE THREAT IS EXPECTED TO CONTINUE OVER THE NEXT
   FEW HOURS. THE WIND DAMAGE THREAT SHOULD AFFECT THE ST LOUIS AREA
   BETWEEN 1045Z AND 1130Z. AN MCS CURRENTLY SAGGING SWD INTO THE
   INSTABILITY AXIS ACROSS SRN IL AND SRN IND SHOULD HELP TO STABILIZE
   THE AIRMASS AHEAD OF THE BOWING LINE-SEGMENT. FOR THIS REASON...THE
   BOW ECHO MAY TEND TO WEAKEN AS IT APPROACHES SRN IND EARLY THIS
   MORNING.
   
   ..BROYLES.. 06/18/2011
   
   
   ATTN...WFO...PAH...ILX...LSX...SGF...EAX...
   
   LAT...LON   38698800 39278882 39969058 40189160 40119249 39609268
               38979268 38089281 37539245 37129148 37039041 37568810
               38698800