Mesoscale Discussion 0436
   NWS Storm Prediction Center Norman OK
   1038 AM CDT Wed Apr 22 2020

   Areas affected...central/eastern Texas and western Louisiana

   Concerning...Severe potential...Watch likely 

   Valid 221538Z - 221745Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Convection across the region will continue to expand in
   coverage, eventually posing a risk of all modes of severe weather
   through the afternoon.  A Tornado Watch will likely be needed for
   portions of the region in the next 1-2 hours.

   DISCUSSION...Satellite/lightning imagery indicates a continued
   increase in convection near the Austin/San Antonio, Texas areas in
   central Texas, with other radar echoes now beginning to show
   northeastward to near Tyler.  Point forecast soundings indicate that
   these storms are currently in an environment characterized by very
   steep mid-level lapse rates (around 8.5 C/km) and strong shear in
   the cloud-bearing layer, suggestive of an elevated supercell threat
   with hail (perhaps significant).  As the region is under the
   glancing influence of a shortwave over northwest Texas, the
   expectation is that this threat will continue to expand spatially
   through the afternoon.  This is also supported by several of the
   latest CAMs.

   Over time, the expectation is that these storms will gradually
   become surface based - especially with eastward extent where modest
   low-level heating (through advection and insolation) will occur
   amidst low 70s F dewpoints.  Very strong low-level shear profiles
   and favorable (cellular) storm mode will also support a tornado/wind
   threat with this activity.  A significant tornado cannot be ruled
   out with any surface-based convection given expected 250-500 m2/s2
   0-3km SRH values.

   Convective trends indicate that a Tornado Watch will be needed
   across portions of the discussion area.

   ..Cook/Hart.. 04/22/2020

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

   ATTN...WFO...LCH...SHV...HGX...FWD...EWX...SJT...

   LAT...LON   30399871 30999843 31949782 32419709 32829581 32799398
               32349326 31629292 30969296 30499408 30009558 29749715
               29849839 30399871