MESOSCALE DISCUSSION 1091
   NWS STORM PREDICTION CENTER NORMAN OK
   0633 PM CDT SAT JUN 20 2015

   AREAS AFFECTED...IA...NRN MO...NWRN IL

   CONCERNING...TORNADO WATCH 319...

   VALID 202333Z - 210030Z

   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 319 CONTINUES.

   SUMMARY...UPWARD EVOLVING SQUALL LINE WILL PROPAGATE SEWD ACROSS
   WW319.

   DISCUSSION...LOW-LEVEL FLOW HAS VEERED CONSIDERABLY AHEAD OF SFC
   COLD FRONT THAT EXTENDS FROM ECNTRL IA...SWWD INTO NWRN MO. 
   CONVECTION HAS GRADUALLY INCREASED ALONG THIS WIND SHIFT OVER THE
   LAST FEW HOURS AND APPEARS TO BE TAKING ON MORE LINEAR
   CHARACTERISTICS THAN DISCRETE.  INSTABILITY IS QUITE STRONG SOUTH OF
   THE FRONT AND DEEP LAYER SHEAR SUFFICIENT FOR MAINTAINING ORGANIZED
   CONVECTION.  GIVEN THE CURRENT TRENDS...IT APPEARS AN EXPANDING
   LINEAR MCS MAY ULTIMATELY EVOLVE ALONG THE FRONT THEN PROPAGATE SEWD
   TOWARD NWRN IL.  LARGE HAIL IS LIKELY OBSERVED WITH ACTIVITY OVER
   MONROE COUNTY IA BUT DAMAGING WINDS COULD MATERIALIZE IF BOWING
   STRUCTURES ULTIMATELY EVOLVE.

   ..DARROW.. 06/20/2015


   ATTN...WFO...ILX...LSX...DVN...DMX...EAX...

   LAT...LON   42289445 41408990 39368989 40269446 42289445