131
ACUS03 KWNS 200735
SWODY3
SPC AC 200734

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0234 AM CDT Mon May 20 2024

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TEXAS
TO THE OHIO VALLEY...

...SUMMARY...
Severe thunderstorms posing a risk for damaging gusts and hail will
be possible from central Texas into the Ohio Valley vicinity on
Wednesday.

...Southern MO/IL into western NY...

An upper shortwave trough over the northern/central Plains will
shift east to the Upper Midwest/Great Lakes vicinity on Wednesday.
This feature, coupled with a southeast-sagging surface front, and
convectively enhanced vorticity maxima floating through
southwesterly deep-layer flow, will focus thunderstorm potential
from portions of southern MO/IL northeast toward the Ohio
Valley/lower Great Lakes vicinity.

Ahead of the surface boundary, a moist and unstable airmass will be
in place (surface dew points in the mid/upper 60s F). Modest
midlevel lapse rates around 7 C/km will also overlap this moist
boundary layer, aiding in moderate destabilization (MLCAPE to 2000
J/kg). Vertical shear will be modest with northeast extent from IN
into western NY, but isolated to widely scattered storms capable of
damaging gusts and perhaps some hail will be possible from afternoon
into the evening.

A corridor of somewhat greater potential may develop across southern
MO/IL during the late afternoon into the nighttime hours.
Instability and vertical shear will likely be stronger here.
Better-organized diurnal convection could congeal into an MCS during
the nighttime hours. However, confidence in this scenario is low,
precluding higher probabilities at this time.

...OK/TX into AR...

An area of broad southwesterly flow will persist across the southern
Plains to the Mid-South. A surface front will extend northeast from
a low over west-central TX into southern MO. Additionally, a dryline
will extend southward from the TX low to the Rio Grande. The
evolution of the surface front is a bit uncertain, but this
boundary, along with the dryline, may focus thunderstorm
development. Capping may suppress convection, but an increasing
low-level jet by evening could result in scattered thunderstorms.
This activity would pose a risk for hail and damaging gusts, with
more conditional tornado risk given capping concerns. One or more
clusters or an MCS may spread southeast with time during the
evening/overnight.

..Leitman.. 05/20/2024

$$