Storm Prediction Center Mesoscale Discussion 991

   Mesoscale Discussion 0991
   NWS Storm Prediction Center Norman OK
   0203 PM CDT Mon May 26 2025

   Areas affected...portions of south-central Texas and the Texas Hill
   Country

   Concerning...Severe potential...Watch likely 

   Valid 261903Z - 262030Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Supercells are expected to develop early this afternoon
   along a rapidly modifying remnant outflow across south-central TX.
   Large to very large hail, damaging gusts and some tornado risk are
   likely. A WW is likely this afternoon.

   DISCUSSION...Across portions of south-central TX and the western
   Hill Country, early afternoon observations showed strong diurnal
   heating was allowing for rapid air mass recovery along and north of
   a remnant outflow boundary. A wavy dryline was also analyzed from
   the TX Big Bend region northwestward into southeastern NM and should
   continue to slowly mix eastward through the early afternoon. As
   broad scale ascent from a southern stream shortwave trough
   overspreads these surface features, a combination of low-level
   convergence and near convective temperatures should result in
   scattered thunderstorm development this afternoon.

   As surface temperatures near 90 degrees, initial incipient
   convective attempts were evident from visible imagery along the
   boundary. The warm temperatures with low 70-s F dewpoints beneath
   8-9 C/km mid-level lapse rates are allowing for large buoyancy with
   3000+ J/kg of MLCAPE. Supercell wind profiles are in place and
   should continue to strengthen into this evening with the approach of
   the shortwave trough. With supercells expected in moderate shear and
   strong buoyancy, large to very large hail (2.5-3.5 in) is likely
   with a few intense storms. Some tornado risk may also develop with
   backed low-level flow near the outflow, and any supercells able to
   persist near the boundary. Damaging wind potential may increase as
   storms begin to cluster.

   Severe potential should increase rapidly early this afternoon as
   storms develop along the dryline and near the modified outflow.
   Storms moving northeastward will mainly pose a hail risk as they
   move deeper into the cooler surface air mass, with surface-based
   storms likely farther south and west. A weather watch will likely be
   needed.

   ..Lyons/Guyer.. 05/26/2025

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

   ATTN...WFO...FWD...EWX...SJT...MAF...

   LAT...LON   29260084 29630147 30110157 30650163 31410237 31460236
               32250181 31900010 31189855 30479818 29379823 28859868
               28790029 29120052 29260084 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN