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Mesoscale Discussion 1111
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   Mesoscale Discussion 1111
   NWS Storm Prediction Center Norman OK
   0342 PM CDT Wed Jun 21 2017

   Areas affected...Parts of southern Louisiana/Mississippi/Alabama and
   the western Florida panhandle

   Concerning...Tornado Watch 359...

   Valid 212042Z - 212215Z

   The severe weather threat for Tornado Watch 359 continues.

   SUMMARY...Occasional low-topped supercell development with risk for
   short-lived tornadoes will continue across north central Gulf
   coastal areas into early evening.

   DISCUSSION...The recent increase in vigorous cellular convective
   development with embedded mesocyclones, near coastal
   Mississippi/Alabama and the western Florida panhandle, appears to be
   accompanying the approach of a low-level speed maximum (50+ kt at
   850 mb).  This has contributed to the enlargement of low-level
   hodographs in the presence of peak boundary layer instability
   near/inland of the coast.  This enhancement of activity may persist
   another couple of hours, before the perturbation shifts inland of
   coastal areas areas, where persistent convective cloud cover and
   precipitation is maintaining more stable boundary layer conditions.

   Meanwhile, 2 mb 2-hour surface pressure falls are now noted near
   southern Louisiana coastal areas, just ahead of the center of Cindy.
   As the cyclonic circulation continues to slowly approach this area,
   strengthening low-level flow and shear may contribute to increasing
   favorable conditions for low-topped supercells with risk for
   tornadoes across portions of south central and southeast Louisiana
   coastal areas by 00-02Z.

   ..Kerr.. 06/21/2017

   ...Please see for graphic product...


   LAT...LON   30239170 30069066 30078977 30428881 31068778 31048670
               30388651 30078778 28968908 28818949 29029068 29309157
               29809190 30239170 

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