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Mesoscale Discussion 865
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   Mesoscale Discussion 0865
   NWS Storm Prediction Center Norman OK
   0116 PM CDT Sat May 27 2017

   Areas affected...Portions of far southeastern MO...southern IL...far
   southwestern IN...and western KY/TN

   Concerning...Severe potential...Watch likely 

   Valid 271816Z - 271915Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Increasing severe potential is quickly increasing, with
   large hail and damaging winds the main threats. Isolated tornadoes
   will also be possible. Watch issuance likely soon.

   DISCUSSION...A strongly unstable airmass exists across the
   discussion area, with strong diurnal heating, ample low-level
   moisture, and steep mid-level lapse rates all contributing to MLCAPE
   of 2000-3500 J/kg per 18Z RAP Mesoanalysis. A belt of enhanced
   mid-level westerly winds exists along and generally south of a
   stalled front that extends across southern IL/IN, with effective
   bulk shear values of 35-50 kt present. Thunderstorms will likely
   form along the stalled front, as well as along an outflow boundary
   from morning convection across TN. Additional ongoing convection
   will likely move into this region from southern/central MO over the
   next several hours. Large hail and damaging winds appear likely with
   this activity, and watch issuance will be needed soon. An isolated
   tornado or two may also occur if convection can remain discrete,
   although numerous to widespread damaging winds will likely become
   the main threat later this afternoon as one or more damaging line of
   thunderstorms moves across this region.

   ..Gleason/Hart.. 05/27/2017

   ...Please see for graphic product...


   LAT...LON   36958697 35698805 35718878 35918982 36529030 38058970
               38528944 38498802 38548675 36958697 

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