SPC AC 250757

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0157 AM CST Tue Dec 25 2018

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST
   TEXAS INTO CENTRAL LOUISIANA...

   ...SUMMARY...
   Scattered severe thunderstorms are possible Thursday over southeast
   Texas into central Louisiana.  Damaging winds and a tornado or two
   are the primary severe risks.

   ...Synopsis...
   A mid-level low/shortwave trough over the central Great Plains will
   weaken as it moves into the Upper Midwest.  A broad belt of strong
   southwesterly 500mb flow (60-80kt) will extend from the western Gulf
   Coast northward into the lower OH Valley.  A low-amplitude
   disturbance, initially located the base of the larger-scale trough,
   will move from southwest TX/Chihuahua into the lower MS Valley late
   Thursday night.  In the low levels, a surface low will occlude as it
   moves into the Upper Midwest with a trailing cold front draping
   south through the Ozarks and into the northwest Gulf Coast.  

   ...Southeast TX east into western AL...
   An extensive ongoing thunderstorm band over eastern/southeast TX is
   expected to move into LA during the late morning.  A very strong
   southerly low-level jet will facilitate moisture return into LA and
   result in middle 60s dewpoints probably reaching into the southern
   half of LA.  Despite relatively weak lapse rates, MLCAPE ranging
   from 250-1000 J/kg and decreasing northward, is forecast within a
   strong low- and deep-shear environment.  Isolated damaging gusts are
   possible but will likely focus near any rear inflow jets with the
   mature squall line.  Although the environment would conditionally
   support supercells ahead of the expected squall line, it is more
   probable only a QLCS with damaging gusts is manifested.  By the
   afternoon, the deep-layer cyclone will become increasingly displaced
   from the lower MS Valley.  A continued risk for isolated severe may
   spread into MS and western AL, but confidence on the magnitude and
   coverage of severe is less certain.

   ..Smith.. 12/25/2018

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