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Mesoscale Discussion 863
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   Mesoscale Discussion 0863
   NWS Storm Prediction Center Norman OK
   1250 PM CDT Sat May 27 2017

   Areas affected...Portions of central/eastern KY...middle/eastern
   TN...southern IN/OH...western WV...and far western VA

   Concerning...Severe potential...Watch possible 

   Valid 271750Z - 271915Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Large hail and damaging wind threat will increase with
   thunderstorms developing along an outflow boundary and stalled front
   this afternoon. Watch issuance is possible within the next several

   DISCUSSION...Visible satellite and radar imagery depict an outflow
   boundary from earlier convection extending from parts of
   south-central KY into northern middle TN. The airmass downstream of
   this boundary has destabilized with temperatures warming into the
   upper 70s and lower 80s, and dewpoints in the mid to upper 60s.
   Steep mid-level lapse rates of 7-8 C/km are supporting MLCAPE
   generally 1000-2000 J/kg across this region. A convectively enhanced
   mid-level vorticity maximum moving eastward this afternoon will
   likely encourage scattered thunderstorms to form along the outflow
   boundary over the next several hours. Additional thunderstorms will
   likely develop along a stalled front across southern OH into WV. A
   belt of strong westerly mid-level winds of 40-50 kt (locally higher)
   associated with the low amplitude shortwave trough/vorticity maximum
   and a veering wind profile with height is resulting in effective
   bulk shear values of 35-55 kt, stronger across KY/TN. This expected
   combination of moderate to strong instability with sufficient shear
   will support supercell structures, with both a large hail and
   damaging wind threat. Eventual growth into clusters/line segments is
   probable, with perhaps a greater damaging wind threat later this
   afternoon if this occurs.

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

   ...Please see for graphic product...


   LAT...LON   36888250 36058351 35878402 35998493 36258561 36688638
               37108682 37638678 38648654 39088578 39748391 39748265
               39488116 39188102 37888143 37398197 36888250 

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