MESOSCALE DISCUSSION 1504
   NWS STORM PREDICTION CENTER NORMAN OK
   0658 AM CDT TUE JUL 17 2007
   
   AREAS AFFECTED...ERN IA...NW IL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 526...
   
   VALID 171158Z - 171330Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 526
   CONTINUES.
   
   A SEVERE THREAT WILL LIKELY CONTINUE ACROSS NW IL SPREADING SEWD
   INTO CNTRL IL OVER THE NEXT 1 TO 3 HOURS. A FEW DAMAGING WIND GUSTS
   AND HAIL WILL BE POSSIBLE AS WELL AS VERY HEAVY RAIN. HOWEVER...THE
   THREAT SHOULD BECOME INCREASINGLY MARGINAL WITH TIME AND A WW IS NOT
   ANTICIPATED SOUTHEAST OF WW 526.
   
   A WELL-DEFINED BOWING LINEAR MCS IS LOCATED IN NW IL JUST TO THE
   NORTHEAST OF A STATIONARY FRONT DRAPED NW TO SE ACROSS THE REGION. 
   OBJECTIVE ANALYSIS SHOWS A 40 KT MID-LEVEL JET JUST UPSTREAM FROM
   THE MCS WITH THE EXIT REGION LOCATED JUST TO THE REAR OF THE BOW.
   THIS IS LIKELY SUPPORTING THE MCS AND THE BOW SHOULD CONTINUE TO
   PERSIST FOR SEVERAL MORE HOURS. HOWEVER...THE LINEAR SYSTEM APPEARS
   TO BE MOVING AWAY FROM THE HIGHER INSTABILITY ACROSS ERN IA. THIS
   FACTOR ALONG WITH THE TIME OF DAY SUGGESTS THAT THE INTENSITY OF THE
   MCS WILL BECOME INCREASINGLY MARGINAL WITH TIME THIS MORNING. A FEW
   DAMAGING WIND GUSTS AND VERY HEAVY RAIN APPEAR TO BE THE MAIN
   THREATS OVER THE NEXT FEW HOURS.
   
   ..BROYLES.. 07/17/2007
   
   
   ATTN...WFO...LOT...ILX...DVN...
   
   40939120 41119031 41568979 42118958 41888902 41588857
   41028824 40508834 40098873 39868929 39889016 40209072
   40619114