Mesoscale Discussion 1598
   NWS Storm Prediction Center Norman OK
   0241 PM CDT Thu Aug 27 2020

   Areas affected...southeast LA...southern into northern MS...eastern
   AR...southwestern TN

   Concerning...Tornado Watch 454...

   Valid 271941Z - 272115Z

   The severe weather threat for Tornado Watch 454 continues.

   SUMMARY...Tornado watch #454 will expire at 4pm CDT.  A new tornado
   watch will likely not be issued immediately following the end of
   tornado watch #454.  A highly conditional risk for a tornado will
   continue but specific details are uncertain.

   DISCUSSION...Radar mosaic shows a rain shield across AR in
   association with Laura as it moves north-northeast.  Farther
   southeast, a decayed band of convection extends from northern MS
   into east-central MS.  Farther south, linearly oriented convection
   with outflow-dominate tendencies extends from far southeast LA to
   the MS coast.  The airmass from the LA/MS coast northward to the
   greater Memphis area is warm/moist with lower 80s temperatures and
   mid-upper 70s F dewpoints.  However, the lack of sustained
   convective development within the eastern half of Tropical Storm
   Laura's remnants, are suggestive of implied large-scale descent. 
   This appears to be supported by water-vapor imagery/objective
   analysis fields showing the upper PV anomaly moving northeastward
   into northwest MS and eastern AR away from the Gulf Coast.  

   Farther north in eastern AR/western TN, the widespread rain shield
   has limited the ability for destabilization despite very moist
   profile.  The hodographs across this region (KNQA) remain very
   strongly sheared but the lack of robust updraft development has
   nullified the risk for a tornado through the mid afternoon. 
   Although highly conditional, if cellular updrafts can emerge on the
   south flank of the rain shield, a localized mini supercell tornado
   risk may evolve for a few hours.

   ..Smith.. 08/27/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...MOB...MEG...JAN...LIX...LZK...

   LAT...LON   29289037 30628939 32578966 32829123 33159176 35739064
               35578984 32998870 29228917 29289037