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Mesoscale Discussion 80
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   Mesoscale Discussion 0080
   NWS Storm Prediction Center Norman OK
   0637 PM CST Fri Jan 20 2017

   Areas affected...southeast Texas through southwest Louisiana

   Concerning...Severe potential...Watch possible 

   Valid 210037Z - 210230Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Threat for mainly a few instances of damaging wind and
   large hail will persist over southeast TX next couple hours,
   spreading into southwest LA by mid evening. With time threat for a
   few tornadoes is expected to increase, especially across southern

   DISCUSSION...Early this evening a warm front separating rich Gulf
   moisture from modified continental-polar air extends from southeast
   LA westward to along the southeast TX coast. This boundary should
   slowly develop inland, especially later tonight as the low-level jet
   strengthens across LA. In the meantime, thunderstorms are expected
   to continue developing initially over southeast TX, but spreading
   into southwest LA by mid evening as a northeastward-ejecting
   shortwave trough enhances ascent north of this boundary. As steeper
   mid-level lapse rates advect eastward in the presence of low-level
   theta-e advection, instability will increase and the thermodynamic
   environment should become more supportive of robust updrafts. Strong
   effective bulk shear will support some supercell and bowing
   structures with initial threats being mainly large hail and damaging
   wind. Weak low-level winds may initially limit short-term tornado
   potential. However, the tornado threat is expected to increase by
   mid-evening onward and especially later tonight over southern LA as
   the strengthening low-level jet augments 0-1 km hodograph size.

   ..Dial/Edwards.. 01/21/2017


   LAT...LON   29759328 29709399 29489470 30089500 30839411 31009278
               30659198 29879202 29759328 

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