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Mesoscale Discussion 259
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MD 259 graphic

   Mesoscale Discussion 0259
   NWS Storm Prediction Center Norman OK
   1228 PM CDT Fri Mar 15 2024

   Areas affected...Portions of south-central and southeast Texas

   Concerning...Severe potential...Watch likely 

   Valid 151728Z - 152000Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Severe storms capable of producing very large hail (2+
   inch) and severe winds are expected across portions of south-central
   and southeast Texas this afternoon. A watch will likely be issued in
   the next couple hours for parts of the area.

   DISCUSSION...Latest surface observations and visible satellite
   imagery indicate an east/west-oriented outflow-modified cold front
   gradually stalling across parts of south-central into southeast TX
   this afternoon. Given that much of this area is on the backside of a
   departing shortwave trough moving east-northeastward across east TX,
   overall coverage of storms is a bit uncertain. Nevertheless, as the
   frontal circulation intersects a gradually deepening moist layer
   amid pockets of diurnal heating, at least isolated to widely
   scattered storm development is expected this afternoon -- possibly
   aided by weak low-level warm advection atop the frontal surface/cold
   pool. An additional focus for storm development will be over the
   southern portion of the Edwards Plateau, where the front intersect
   the higher terrain amid upslope flow enhancements.

   The latest ACARS soundings from San Antonio TX sampled steep
   midlevel lapse rates (near 8 C/km) associated with an EML atop a
   gradually deepening moist layer extending through 1 km AGL.
   Continued diurnal heating of this moist layer should contribute to 
   moderate/strong instability (2500-3000 J/kg MLCAPE). In addition, a
   belt of 40-50 kt midlevel west-southwesterly flow above veering
   low-level flow will yield 40-50 kt effective shear. This will
   support the development of initially semi-discrete supercell
   clusters, capable of producing very large hail (some greater than
   baseball-sized), along with locally severe winds. While a tornado or
   two cannot be entirely ruled out with these storms, low-level shear
   will not be particularly strong, and the development of strong cold
   pools could reduce the risk to an extent. With time, localized
   upscale growth into several organized clusters is possible, with an
   increasing wind risk and continued large hail threat with
   east-southeastward extent.

   ..Weinman/Goss.. 03/15/2024

   ...Please see for graphic product...


   LAT...LON   29110097 29450126 29890135 30100106 30140073 30049826
               30169736 30359635 30449568 30439523 30329461 30039456
               29589492 29139556 28829632 28699705 28639790 28609943
               28720015 28860062 29110097 

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