Mesoscale Discussion 1915
   NWS Storm Prediction Center Norman OK
   1250 PM CDT Wed Oct 27 2021

   Areas affected...southern Louisiana through southern Mississippi

   Concerning...Tornado Watch 540...

   Valid 271750Z - 271915Z

   The severe weather threat for Tornado Watch 540 continues.

   SUMMARY...Threat for damaging wind and tornadoes including potential
   for a couple of strong tornadoes should persist over southern LA,
   spreading east through southeast LA and southern MS during the
   afternoon. A new tornado watch will likely be needed for this area
   by 19Z.

   DISCUSSION...A line of storms with embedded bowing segments and some
   supercell structures continues moving through western LA at around
   35 kt. East of this line the warm sector continues to expand
   northward south of a warm front that extends from southeast through
   north central LA. A very moist boundary layer is in place south of
   this front with mid 70s F dewpoints, and diabatic warming has
   boosted surface temperatures into the low to mid 80s F supporting up
   to 2000 J/kg MLCAPE. Several northwest-southeast oriented
   convergence bands are evident on visible imagery extending into
   southern LA from the Gulf. The 18Z RAOB from Slidell modified for
   surface conditions in warm sector indicates minimal inhibition. This
   suggests that, in addition to the arrival of the line of storms, the
   potential will exist for discrete storms develop as the boundary
   layer continues to destabilize. The low-level jet is forecast to
   undergo further strengthening, supporting large hodographs with 0-1
   km storm relative helicity from 250-350 m2/s2. Threat for damaging
   wind and tornadoes will persist through the remainder of the
   afternoon into early evening in this region.

   ..Dial/Thompson.. 10/27/2021

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

   ATTN...WFO...MOB...JAN...LIX...LCH...SHV...

   LAT...LON   29709288 30359283 31129279 31429201 31599145 31848993
               31568868 30548864 29309009 29399090 29709174 29709288