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Mesoscale Discussion 798
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   Mesoscale Discussion 0798
   NWS Storm Prediction Center Norman OK
   0741 AM CDT Sat May 20 2017

   Areas affected...Southern Texas

   Concerning...Severe potential...Watch possible 

   Valid 201241Z - 201415Z

   Probability of Watch Issuance...40 percent

   SUMMARY...At least isolated severe hail and wind are expected
   through morning.

   DISCUSSION...A small complex of thunderstorms continues to redevelop
   along a slow moving front/outflow boundary west and northwest of the
   San Antonio area. Several of these storms have contained hail, but
   few have remained very long-lived as they have been progressively
   undercut by outflow. Recently a small line segment has materialized,
   suggesting a bit more outflow surge. 

   A very moist and unstable air mass is in place across the region,
   and daytime heating will lead to further destabilization and also
   increased storm propagation. Morning soundings also show relatively
   long hodographs owing to good mid to upper level flow, however,
   winds in the lower part of the troposphere are relatively weak,
   though veering with height.

   Daytime heating should allow for a gradual increase in storm
   coverage and intensity as they progress east/southeastward across
   south TX. Large hail and damaging winds will be possible, and a
   watch may be needed later this morning as these storms evolve.

   ..Jewell/Guyer.. 05/20/2017

   ...Please see for graphic product...


   LAT...LON   30019954 30189851 30159822 29839715 29429677 28879624
               28439621 28049648 27759701 27729750 27999826 28629920
               29059957 29199977 29369984 29609983 29819970 30019954 

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