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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