SPC AC 240715

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0215 AM CDT Sun Oct 24 2021

   Valid 261200Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE SOUTHERN AND CENTRAL PLAINS...

   ...SUMMARY...
   Isolated to scattered severe thunderstorms associated with large
   hail and wind damage are expected across parts of the southern and
   central Plains from late Tuesday afternoon through the evening into
   the overnight period.

   ...Southern and Central Plains...
   An upper-level trough will move eastward across the southern Rockies
   on Tuesday as mid-level flow remains south-southwesterly across much
   of the Great Plains. This will result in strong moisture advection
   from north Texas into Oklahoma and Kansas, where a corridor of
   moderate instability will likely develop by afternoon. A capping
   inversion should hold convective initiation off until late
   afternoon, when isolated thunderstorms are expected to initiate
   along a dryline from west-central Texas northward into the far
   eastern Texas Panhandle. As large-scale ascent associated with the
   upper-level trough moves into the southern and central Plains during
   the evening, storm coverage should rapidly expand. A line of storms
   is forecast to become organized and move east-northeastward across
   north-central Texas and central Oklahoma. Additional thunderstorms
   are expected to initiate during the evening from central Kansas into
   southern Nebraska. All of this activity could organize into an MCS
   during the evening and overnight period.

   Model forecasts are in relatively good agreement concerning the
   timing of the upper-level trough and distribution of instability.
   MLCAPE is generally forecast to reach the 1000 to 2000 J/kg range to
   the east of the dryline. In addition, moderate deep-layer shear
   should be in place across parts of the southern Plains and central
   Plains. This should support supercell development with cells that
   remain discrete. However, a mixed mode is expected with multicells
   and organized line segments possible as well. Supercells will be
   capable of producing large hail and wind damage. Damaging wind gusts
   and hail will also be possible with the more intense line segments.
   A tornado threat may also develop across parts of the southern and
   central Plains, mainly where localized conditions become favorable
   and low-level shear becomes maximized. The severe threat should be
   more isolated across central and eastern Nebraska because
   instability should be weaker and convective initiation could occur
   late.

   ..Broyles.. 10/24/2021

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