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Mesoscale Discussion 1264
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   Mesoscale Discussion 1264
   NWS Storm Prediction Center Norman OK
   0804 PM CDT Fri Jul 07 2017

   Areas affected...Portions of southwestern SD...western
   NE...northeastern CO...and northwestern KS

   Concerning...Severe potential...Watch unlikely 

   Valid 080104Z - 080300Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Widely spaced thunderstorms may pose an isolated severe
   threat through the remainder of the evening. Watch issuance is

   DISCUSSION...Within a corridor a greater low-level moisture oriented
   from western SD to western KS, isolated convection has developed
   over the past several hours. The ongoing thunderstorms across
   southwestern SD may be related to ascent attendant to a ribbon of
   mid-level vorticity evident in water vapor satellite imagery. The
   environment across this region will support supercell structures
   with both a large hail and damaging wind threat, as MLCAPE ranges
   from 500-2000 J/kg and effective bulk shear of 35-50 kt encourages
   updraft organization. One of these supercells across northwestern KS
   has produced up to golf ball sized hail, and MRMS max hail size
   estimates hail up to 2.5 inches in diameter may be occurring with
   this thunderstorm as of 01Z. Other ongoing convection across
   northeastern CO will gradually spread into the better thermodynamic
   and kinematic environment over the next several hours, and may also
   pose an isolated severe threat. It is not clear if any of these
   widely spaced thunderstorms will be able to grow upscale into a
   small bowing line complex given only a modest increase in southerly
   low-level flow that is forecast to occur this evening. Still, there
   may be some potential for upscale growth with the activity emanating
   from northeastern CO eventually merging with the isolated supercell
   over northwestern KS. Regardless, current thinking is that the
   overall severe risk across this region should remain too isolated to
   warrant watch issuance, but radar trends will be monitored through
   the evening.

   ..Gleason/Thompson.. 07/08/2017

   ...Please see for graphic product...


   LAT...LON   43760371 44070299 44160216 42880108 40950065 39180069
               38700133 38710255 39590339 41070390 43300393 43760371 

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