Mesoscale Discussion 0154
   NWS Storm Prediction Center Norman OK
   1050 AM CST Wed Mar 04 2020

   Areas affected...Portions of far eastern Texas into central
   Louisiana and central Mississippi

   Concerning...Severe Thunderstorm Watch 42...43...

   Valid 041650Z - 041845Z

   The severe weather threat for Severe Thunderstorm Watch 42, 43
   continues.

   SUMMARY...The threat for a few damaging wind gusts and occasional
   large hail will continue for the next few hours. Convective trends
   will continue to be monitored for the need of additional watches
   past WW 042/043 expiration time at 18Z.

   DISCUSSION...A 500 mb cutoff low and subsequent modest upper-level
   support will gradually drift eastward across TX this afternoon. In
   response, strong 850-700 mb WAA has promoted both deep-layer ascent
   and elevated buoyancy (1000+ J/kg MUCAPE per 16Z Mesoanalysis) to
   support sustained elevated convection north of a quasi-stationary
   surface baroclinic zone. Over the past few hours, a few areas of
   organized, marginally severe hail-producing convection have been
   noted, including elevated bowing segments in central MS and in the
   Houston/Walker County TX vicinity. These storms are rooted along the
   850 mb baroclinic zone, and given the approach of the upper-low and
   constant feed of low-level moist/unstable air, these segments are
   expected to continue for the next few hours. With strong deep-layer
   shear also in place, these segments may also remain organized and
   intense enough to promote isolated damaging wind gusts as well as
   marginally severe hail. In addition, strong low-level shear (200+
   m2/s2 effective SRH) coincides with an unstable surface airmass
   along the surface baroclinic zone across portions of southern LA
   into southern MS, and any storm that root in the boundary layer and
   latch unto the boundary may produce a tornado.

   Later into the afternoon though, the upper-low and associated
   associated mid-level ascent will lag the eastward movement of the
   WAA axis, suggesting a gradual west-to-east weakening trend in
   convection, as supported by 12Z HREF and the latest 12Z HRRR runs.
   As such, convective trends will continue to be monitored for the
   need of additional watch issuance later this afternoon.

   ..Squitieri/Hart.. 03/04/2020

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

   ATTN...WFO...JAN...LIX...LCH...SHV...HGX...FWD...

   LAT...LON   32558918 31848907 31318923 30848966 30609007 30509110
               30399411 30679481 30949540 31179559 31479553 31769504
               31789482 32399304 32558918