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Mesoscale Discussion 869
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   Mesoscale Discussion 0869
   NWS Storm Prediction Center Norman OK
   0316 PM CDT Sat May 27 2017

   Areas affected...Portions of central/southern VA and northern NC

   Concerning...Severe potential...Watch possible 

   Valid 272016Z - 272145Z

   Probability of Watch Issuance...40 percent

   SUMMARY...An isolated severe risk may develop late this afternoon
   and continue into this evening. Large hail and strong to locally
   damaging wind gusts would be the main threats. Watch issuance is

   DISCUSSION...20Z surface analysis shows a remnant front stalled
   across northern into southeastern VA. Strong diurnal heating of a
   moist low-level airmass has resulted in weak to locally moderate
   instability, and MLCAPE generally ranges from 500-1500 J/kg along
   and south of the front. Water vapor satellite imagery shows a
   low-amplitude, convectively enhanced shortwave trough moving over
   the central Appalachians as of 20Z. Modifying the 18Z sounding from
   RNK for current observations shows the mid-level inversion centered
   on 700 mb is almost completely eroded, and convection has begun to
   recently increase in coverage and intensity along/near the higher
   terrain of central/southern VA. 0-6 km bulk shear values of 40-50 kt
   per latest RAP Mesoanalysis and FCX VWP will easily support
   supercells. Isolated large hail and strong to locally damaging winds
   will be possible with the strengthening convection across this
   region. Recent operational HRRR runs suggest convection may attempt
   to grow upscale into one or more line segments through this evening,
   which could enhance the damaging wind threat. Watch issuance is
   possible over the next several hours depending on radar trends.

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

   ...Please see for graphic product...


   LAT...LON   36818010 38427919 38697859 38317744 37747702 36497709
               36147765 36067881 36077963 36358004 36818010 

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