Mesoscale Discussion 0831
   NWS Storm Prediction Center Norman OK
   1007 PM CDT Mon May 31 2021

   Areas affected...The Rio Grande River vicinity of south central
   Texas

   Concerning...Severe Thunderstorm Watch 231...

   Valid 010307Z - 010430Z

   The severe weather threat for Severe Thunderstorm Watch 231
   continues.

   SUMMARY...An organizing cluster of thunderstorms may pose increasing
   risk for strong surface gusts across the Rio Grande River vicinity
   between Del Rio and Laredo, into adjacent portions of southern Texas
   through 11 PM-1 AM CDT.  Trends are being monitored for the
   possibility of an additional severe weather watch to the south of
   Severe Thunderstorm Watch 231.

   DISCUSSION...The northern (now southwest of Del Rio, TX) of a pair
   of southeastward propagating supercells appears to be undergoing
   upscale growth, with convection beginning to increase along the
   leading edge of strong convective outflow to the south of the
   mid-level cyclonic circulation center.  A moist boundary layer
   (including surface dew points just above 70F) near the Rio Grande
   River, into the higher terrain west of the river, remains
   characterized by mixed-layer CAPE in excess of 2000 J/kg, with CAPE
   perhaps as large as 1500 J/kg into areas just southwest of San
   Antonio and west of Brownsville.  25-30 kt southeasterly inflow of
   this air mass may support considerable further upscale growth during
   the next couple of hours. 

   Based on evening soundings, lower/mid-levels may be unsaturated
   enough to allow for sufficient cold pool strengthening to support
   increasing potential for strong to severe winds along an
   accelerating gust front.  If this occurs, areas across and east of
   the Rio Grande River, particularly near and east through south of
   Eagle Pass, will be increasingly impacted through 04-06Z.

   ..Kerr.. 06/01/2021

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

   ATTN...WFO...CRP...EWX...

   LAT...LON   29340052 29269978 28529910 27379957 27360021 27840101
               28350144 28570112 29340052