Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Sep 23 2023 04:53:33

ACUS02 KWNS 230453
SWODY2
SPC AC 230452

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1152 PM CDT Fri Sep 22 2023

Valid 241200Z - 251200Z

....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS AND ARK-LA-TEX...

....SUMMARY...
Thunderstorms, associated with large hail and wind damage, will be
possible on Sunday from parts of north-central Texas northeastward
into southeast Oklahoma and western Arkansas.

....Southern Plains/Ark-La-Tex...
An upper-level trough will move through the Great Plains on Sunday,
as divergent flow aloft remains over the southern Plains and
Ark-La-Tex. Ahead of the trough, a moist airmass will be in place
throughout much of the southern Plains, Ark-La-Tex and lower
Missouri Valley. A cold front will advance southeastward across the
southern Plains, being positioned from west-central and north Texas
into far southeast Oklahoma by afternoon. Ahead of the cold front, a
capping inversion will prohibit convective initiation for much of
the day. As the cap weakens during the late afternoon, isolated to
scattered thunderstorms are expected to develop. Convective coverage
is forecast to rapidly expand along and near the front by early
evening, with several organized clusters likely persisting into the
mid evening. MCS development will be possible across the parts of
the southern Plains and Ark-La-Tex during the evening.

Across the moist airmass, moderate to strong instability is expected
to be in place by afternoon, with MLCAPE most likely peaking in the
2000 to 3500 J/kg range in most areas. Within this unstable airmass,
moderate deep-layer shear will be prevalent. Forecast soundings by
00Z/Monday in north Texas from Wichita Falls to the Dallas/Fort
Worth Metroplex have 0-6 km in the 45 to 55 knot range, owing to
directional shear in the low levels and speed shear in the mid
levels. 700-500 mb lapse rates are forecast to be between 7.5 and 8
C/km. This environment will be favorable for supercells with
isolated large hail. Large surface temperature-dewpoint spreads will
result in high storm bases. Nearly dry adiabatic temperatures from
the surface to near 850 mb will contribute to downdraft
acceleration, making wind damage a possibility with the stronger
storms. The severe threat should persist through the early to mid
evening, as a large cluster or MCS moves southeastward across the
Red River Valley and Ark-La-Tex.

...Broyles.. 09/23/2023

$$

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