Mesoscale Discussion 0063
   NWS Storm Prediction Center Norman OK
   1243 PM CST Sat Jan 18 2020

   Areas affected...portions of southern MS and adjacent southeastern
   LA

   Concerning...Severe potential...Watch unlikely 

   Valid 181843Z - 182045Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Isolated and transient low-topped marginal supercells
   possible the next few hours. Overall threat is expected to remain
   sub-severe.

   DISCUSSION...Showers have periodically intensified in area of low
   level confluence ahead of the front across southern MS early this
   afternoon. This convection has been relatively low-topped, up to
   around 20 kft and is not producing lightning. However, forecast
   soundings and 18z mesoanalysis indicate effective shear values
   (25-40 kt) favorable for organized, marginal supercell structures.
   This is further supported by VWP data from the DGX 88-D, which shows
   a small, but favorably curved low-level hodograph.

   Overall these features have been rather transient, developing in an
   area where stronger surface heating has occurred in thinner cloud
   cover. Temperatures across parts of far southern MS into adjacent
   southeast LA have warmed into the low 70s F, with dewpoints in the
   mid 60s F, resulting in MLCAPE values as high as 500 J/kg. This
   should support continued periodic intensification of showers and
   isolated thunderstorms through the afternoon ahead of the surface
   cold front. However, shear is expected to decrease throughout the
   remainder of the daytime hours and the overall environmental
   parameter space is probably at its most favorable now through the
   next 2-3 hours. Any severe threat is expected to remain limited in
   time and space and any stronger cells are expected to remain
   transient/sporadic.

   ..Leitman/Guyer.. 01/18/2020

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

   ATTN...WFO...MOB...JAN...LIX...

   LAT...LON   30609021 30579081 30779126 30989141 31319138 31789088
               31929036 31978998 31968934 31668892 31378880 31248883
               30828958 30668995 30609021