SPC AC 261740

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1240 PM CDT Tue May 26 2020

   Valid 271200Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   CENTRAL TEXAS...

   ...SUMMARY...
   Severe thunderstorms are expected across portions of central Texas
   Wednesday afternoon through Wednesday evening, with lesser
   severe-weather potential over parts of the central Gulf Coast
   region, and coastal Carolinas.

   ...Synopsis...
   A large/slow-moving upper low -- centered over the Arklatex vicinity
   -- will remain the dominant feature of interest over the U.S. this
   period, with rather high-amplitude ridging (over the western
   Atlantic and southwestern U.S.) flanking this low on either side.

   At the surface, a relatively weak/nondescript pattern will prevail. 
   A weak low should evolve over central Texas as a vorticity lobe
   pivots southeastward around the upper low, while a second/weak low
   drifts northward near the southeastern U.S. coast.  

   ...Central Texas...
   Weak low pressure development is expected to occur over the Texas
   South Plains area early Wednesday and then drift eastward into
   central Texas with time, as a lobe of vorticity -- and associated
   mid-level speed max -- rotate southeastward around the upper low. 
   As this occurs, low-level flow will turn southerly across roughly
   the southern half of Texas, with a weakly baroclinic convergence
   zone expected to evolve in a west-northwest to east-southeast
   orientation across central Texas by afternoon.

   Northward advection of higher theta-e air at low levels beneath
   rather steep mid-level lapse rates will combine with daytime heating
   to yield moderate afternoon destabilization, with mixed-layer CAPE
   climbing into the 2000 to 2500 J/kg range.  This will support storm
   development by mid afternoon near the low and associated convergence
   zone, as DPVA spreads southeastward across central Texas.

   Given favorable shear expected to evolve with time (southerly to
   south-southeasterly low-level winds veering/increasing to 50-plus kt
   from the northwest at mid levels), storms should quickly
   organize/acquire rotation.  As such -- and aided by the increasingly
   unstable environment -- very large hail will be possible with the
   initial supercellular storm development, along with risk for locally
   damaging winds and a couple of tornadoes.  With time, some upscale
   growth of storms is possible, into a mix of both cellular and banded
   modes.  Damaging wind potential may increase into early evening with
   some potential for southeastward propagation of convective bands,
   before the activity peaks, and then begins to diminish, into the
   evening hours.

   ...Central Gulf Coast area...
   As a vorticity lobe -- associated with a 50 kt mid-level jet streak
   -- rotates around the upper low into the central Gulf Coast region,
   afternoon thunderstorm development is expected across the area. 
   Questions persist as to the degree of destabilization that will
   occur given rather weak lapse rates aloft, and low-level convergence
   appears likely to remain weak overall, without a well-defined
   synoptic surface boundary.  Still, with mid-level flow increasing
   with time, shear will be sufficient to support updraft organization.
    As such, a few stronger storms may evolve across parts of eastern
   Louisiana and southeast Mississippi,spreading northeastward across
   parts of Alabama and vicinity through the afternoon.  Given
   associated potential for hail/wind with a couple of the stronger
   cells, parts of the area are being upgraded to MRGL risk.

   ...Coastal South Carolina/adjacent southeastern North Carolina...
   A weak surface low near the southern SC coast at the beginning of
   the period is forecast to drift northward throughout the day. 
   Showers and a few thunderstorms on the northern and eastern
   periphery of the low should continue spreading inland from the
   western Atlantic, within a modestly unstable onshore environment. 
   Enhanced southeasterly low-level winds may support some low-level
   rotation, with a brief tornado and/or locally strong wind gusts
   possible, particularly through the morning and into the afternoon
   hours.

   ..Goss.. 05/26/2020

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