Mesoscale Discussion 0495
   NWS Storm Prediction Center Norman OK
   0904 PM CDT Tue Apr 28 2020

   Areas affected...western portions of deep south TX.

   Concerning...Severe potential...Watch unlikely 

   Valid 290204Z - 290400Z

   Probability of Watch Issuance...5 percent

   SUMMARY...Isolated severe-wind and/or hail potential may spread
   across the Rio Grande from Mexico into the Valley area northwest of
   McAllen and southeast of Laredo, before the storms weaken later this
   evening.  Given the limited time and areal extent of the threat, a
   watch is not anticipated at this time.

   DISCUSSION...A loosely organized cluster of strong, possibly severe
   thunderstorms was evident over the Tamaulipas Panhandle, south to
   southwest of LRD, as of 02Z.  Despite some pronounced weaknesses in
   low/middle-level flow above the boundary layer, deep shear over the
   region (e.g., effective-shear magnitudes around 45-55 kt) appears
   favorable for organized multicells and sporadic supercells. 
   However, a combination of clustering modes and stronger capping with
   southeastward extent may limit the duration of supercell structures.
   Observed soundings from CRP and especially BRO showed substantial
   MLCINH, especially with modification to surface conditions for
   expected diabatic cooling.  However, weaker CINH is evident nearer
   to the corridor between MFE-LRD.  When considering forced ascent
   along storm-scale cold pools, convection should cross the Rio Grande
   and affect at least western parts of the discussion area through
   about 04-05Z.

   ..Edwards.. 04/29/2020

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

   ATTN...WFO...CRP...BRO...

   LAT...LON   27409950 27309917 27059847 26699843 26249849 26259866
               26389879 26389906 26419910 26509907 26549919 26819926
               27019945 27219940 27329953 27409950