MESOSCALE DISCUSSION 1668
   NWS STORM PREDICTION CENTER NORMAN OK
   0508 PM CDT FRI SEP 09 2016

   AREAS AFFECTED...PORTIONS OF CNTRL/SRN IL AND CNTRL IND

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 092208Z - 100015Z

   PROBABILITY OF WATCH ISSUANCE...60 PERCENT

   SUMMARY...AN ISOLATED TORNADO THREAT MAY INCREASE OVER THE NEXT
   SEVERAL HOURS. TORNADO WATCH ISSUANCE REMAINS POSSIBLE.

   DISCUSSION...DETAILED METEOROLOGICAL REASONING PROVIDED IN PREVIOUS
   SWOMCD 1666 REMAINS VALID FOR THIS REGION. LATEST RADAR TRENDS SHOW
   CONVECTION ACROSS PARTS OF SRN/CNTRL IL TO THE E OF THE ST. LOUIS
   METRO EXHIBITING SOME WEAK LOW-LEVEL ROTATION. POOR MID-LEVEL LAPSE
   RATES DO APPEAR TO BE LIMITING UPDRAFT STRENGTH...BUT A WARM AND
   MOIST AIRMASS DOWNSTREAM OF THE ONGOING THUNDERSTORMS AND SOME
   INCREASE IN SLY/SWLY LOW-LEVEL FLOW IS EXPECTED OVER THE NEXT
   SEVERAL HOURS ACROSS THE MCD AREA AS AN UPPER TROUGH APPROACHES FROM
   THE NRN PLAINS/UPPER MIDWEST. EFFECTIVE SRH VALUES ARE FORECAST TO
   GENERALLY INCREASE INTO THE 150-200 M2/S2 RANGE THROUGH
   APPROXIMATELY 02Z WITH ENOUGH INSTABILITY PRESENT FOR CONVECTION TO
   REMAIN SFC BASED. AN ISOLATED TORNADO THREAT ALONG WITH SOME RISK
   FOR LOCALLY DAMAGING WINDS WILL EXIST WITH THESE THUNDERSTORMS
   THROUGH THE EVENING HOURS...AND TORNADO WATCH ISSUANCE REMAINS
   POSSIBLE.

   ..GLEASON/GUYER.. 09/09/2016


   ATTN...WFO...IND...PAH...ILX...LSX...

   LAT...LON   38969003 40288835 40428639 39878559 39328584 38508790
               38168997 38429016 38969003