MESOSCALE DISCUSSION 1312
   NWS STORM PREDICTION CENTER NORMAN OK
   0408 AM CDT MON JUN 20 2011
   
   AREAS AFFECTED...PARTS OF CENTRAL AND NORTH CENTRAL IL INTO WRN IND
   AND SERN IA
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 519...
   
   VALID 200908Z - 201015Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 519
   CONTINUES.
   
   AN APPARENT DEVELOPING BOW STRUCTURE ACROSS WEST CENTRAL IL WILL BE
   MONITORED FOR FURTHER INCREASE IN FORWARD SPEED.  ENVIRONMENT IS
   CONDUCIVE TO SUPPORT FORWARD PROPAGATION...AND THUS LOCAL WFO
   EXTENSION OF WW 519 MAY BE NEEDED SOON INTO PARTS OF CENTRAL
   IL...GENERALLY FROM CHRISTIAN TO MCLEAN COUNTIES.  IF A FAST MOVING
   BOW DOES DEVELOP...THEN A NEW WW MAY BE REQUIRED BY 10-11Z ACROSS
   PARTS OF CENTRAL IL INTO WRN/SWRN IND.  MEANWHILE...MUCH OF ERN IA
   HAS BEEN CONVECTIVE OVERTURNED...BUT NEW STRONG TO SEVERE STORMS
   DEVELOPING OVER SWRN-SRN IA MAY MOVE INTO WRN PARTS OF WW 519...SUCH
   THAT THE SEVERE WEATHER THREAT MAY NOT BE OVER IN THIS PART OF ERN
   IA.
   
   AT 845Z...REGIONAL RADAR IMAGERY SHOWED A LINE OF TSTMS THAT
   RECENTLY MOVED INTO WEST CENTRAL IL FROM SERN IA/FAR NERN MO AND
   EXTENDED FROM MERCER TO HANCOCK COUNTIES IL.  THIS LINE HAS BEGUN TO
   SHOW INDICATIONS OF A BOWING STRUCTURE WITH THE FORWARD SPEED
   INCREASING DURING THE LAST HOUR TO CLOSE TO 40 KT TOWARD THE ESE.  A
   SECOND BRANCH OF BROAD SRN/CENTRAL PLAINS LLJ EXTENDS INTO THE LOWER
   MO/MID MS VALLEYS WITH WAA EXTENDING FROM NRN MO INTO CENTRAL/SRN
   IL.  THIS COMBINED WITH A DEVELOPING COLD POOL IN THE WAKE OF THE
   WEST CENTRAL BOWING STRUCTURE SHOULD AID IN SUPPORTING THIS TSTM
   COMPLEX AS IT PROGRESSES ESEWD.  A RESERVOIR OF MODERATE INSTABILITY
   EXTENDING FROM MO INTO THE REGION DOWNSTREAM OF THE BOW INCREASES
   THE CONFIDENCE THAT THIS BOW WILL PERSIST TO THE ESE OF WW 519 BY
   10Z.
   
   ..PETERS.. 06/20/2011
   
   
   ATTN...WFO...IND...LOT...ILX...LSX...DVN...DMX...EAX...
   
   LAT...LON   40399251 42329213 42159059 41698906 40798784 40138728
               39218743 38828824 39369021 40399251