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Mesoscale Discussion 920
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   Mesoscale Discussion 0920
   NWS Storm Prediction Center Norman OK
   0100 PM CDT Tue May 30 2017

   Areas affected...A small part of southeast Louisiana (near and north
   of the Gulf of Mexico coast)

   Concerning...Severe potential...Watch unlikely 

   Valid 301800Z - 302030Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A locally greater, though marginal coverage, tornado risk
   exists this afternoon across a small part of southeast Louisiana
   from Terrebonne Parish into mainly central portions of Lafourche
   Parish and southern St. Mary's Parish.  Some potential for this
   marginal threat to develop/spread east into portions of Plaquemines
   Parish later this afternoon to early evening.

   DISCUSSION...Trends in mosaic radar imagery indicated a couple of
   periodic and transient low-level rotational couplets with storms
   across Terrebonne Parish and central Lafourche Parish.  These storms
   were located in vicinity of an east-west oriented outflow boundary,
   which extended from offshore the north-central gulf coast into far
   southeast Louisiana (through central Terrebonne to southern St.
   Mary's Parishes).  A very moist and unstable environment combined
   with vertically veering winds, especially near and north of the
   surface boundary, is enhancing the potential for storm rotation and
   an attendant, mainly brief, tornado threat.  Overall coverage for
   the area affected should remain limited this afternoon, precluding
   higher severe probabilities in the Day 1 Convective Outlook and a
   watch potential.

   ..Peters/Hart.. 05/30/2017

   ...Please see for graphic product...


   LAT...LON   29459172 29719120 29759075 29749036 29698992 29598972
               29388955 29328960 29239029 29269071 29259104 29259126
               29289156 29299172 29459172 

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