MESOSCALE DISCUSSION 0517
   NWS STORM PREDICTION CENTER NORMAN OK
   0536 AM CDT THU APR 18 2013
   
   AREAS AFFECTED...ERN MO...WRN IL
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 181036Z - 181130Z
   
   PROBABILITY OF WATCH ISSUANCE...60 PERCENT
   
   SUMMARY...AN ISOLATED SEVERE THREAT MAY DEVELOP ACROSS PARTS OF ERN
   MO AND WRN IL OVER THE NEXT FEW HOURS. WIND DAMAGE...HAIL AND
   PERHAPS A TORNADO COULD OCCUR WITH THE MORE INTENSE CELLS. WW
   ISSUANCE REMAINS POSSIBLE ACROSS THE MCD AREA EARLY THIS MORNING.
   
   DISCUSSION...A SQUALL-LINE IS CURRENTLY ONGOING ON THE WRN EDGE OF
   THE LOW-LEVEL JET FROM WRN IL EXTENDING SWWD TO NW AR. DISCRETE
   CELLS ARE INITIATING AHEAD OF THE LINE IN SE MO AND THE STORM IN
   WASHINGTON COUNTY MO IS SHOWING SIGNS OF ROTATION. OBJECTIVE
   ANALYSIS SUGGESTS THAT A POCKET OF STRONGER INSTABILITY IS LOCATED
   ACROSS SE MO WHERE SBCAPE VALUES ARE ESTIMATED AROUND 1000 J/KG. IN
   ADDITION...THE WSR-88D VWP AT ST LOUIS SHOWS IMPRESSIVE LOW-LEVEL
   SHEAR WITH LONG LOOPED HODOGRAPHS. THIS ALONG WITH SFC DEWPOINTS IN
   THE MID TO UPPER 60S F WITH LOW-LCL HEIGHTS COULD BE ENOUGH FOR AN
   ISOLATED TORNADO THREAT EARLY THIS MORNING. WIND DAMAGE AND HAIL
   WILL ALSO BE POSSIBLE.
   
   ..BROYLES/HART.. 04/18/2013
   
   
   ATTN...WFO...PAH...LSX...
   
   LAT...LON   38699054 38029102 37779084 37689039 38078953 38978892
               39378977 38699054