561
ACUS01 KWNS 220601
SWODY1
SPC AC 220600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Wed May 22 2024

Valid 221200Z - 231200Z

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

...SUMMARY...
Severe storms with large hail, wind damage and a few tornadoes will
be likely today across parts of the southern Plains and Ark-La-Tex.
Isolated severe storms will be possible today from parts of the mid
Mississippi Valley northeastward into the Ohio Valley and Lower
Great Lakes.

...Southern Plains/Ark-La-Tex...
West-southwest mid-level flow will be in place over a moist and
unstable airmass today across much of the southern Plains and
Ark-La-Tex. At the surface, a cold front will advance southeastward
into southeast Oklahoma and northwest Texas by afternoon. As surface
temperatures and low-level convergence increase along and near the
front, convective initiation will become likely around midday.
Numerous thunderstorms are expected to develop and move
east-southeastward across the southern Plains and Ark-La-Tex during
the afternoon. The development of a large severe MCS appears likely.


Ahead of the front, moderate to strong instability is forecast by
afternoon, with MLCAPE peaking in the 3000 to 4000 J/kg range. In
addition, moderate deep-layer shear is forecast across much of the
moist airmass. At 21Z along and near the axis of greatest convective
potential, forecast soundings from the northern Texas Hill Country
northeastward into the Ark-La-Tex, have 0-6 km shear in the 50 to 60
knot range. This suggests that supercells will be possible, mainly
early in the event when cells are more likely to be discrete and
cell interactions are less likely. In addition, forecast soundings
near the axis of strongest instability, have 700-500 mb lapse rates
in the 7.5 to 8 C/km range. This environment will be favorable for
large hail with supercells, with hailstones of greater than 2 inches
in diameter possible with the strongest of storms. In areas where
cells congeal into a line, wind damage will become likely. The
greatest potential will be with the faster-moving bowing segments. A
few tornadoes are also expected, mainly with supercells and or bow
echoes.

The severe threat is expected to persist into the early to mid
evening, as the linear MCS moves across parts of central and east
Texas into northern Louisiana.

...Ohio Valley/Lower Great Lakes...
A shortwave trough will move northeastward into the western Great
Lakes today, as a northeast-to-southwest oriented pre-frontal trough
advances eastward through the Ohio Valley. A narrow corridor of
instability will develop near the pre-frontal trough from the mid
Mississippi Valley northeastward to the lower Great Lakes. As
surface temperatures warm along the front during the day, isolated
to scattered thunderstorms are expected to initiate. Multiple
thunderstorm clusters are expected to develop and move eastward
through the Ohio Valley during the afternoon. Forecast soundings at
21Z along the axis of instability from western Kentucky
northeastward into central Ohio generally have 0-6 km shear in the
35 to 45 knot range. This, combined with MLCAPE near 2000 J/kg, will
support a potential for organized severe storms. Although supercells
will be possible, there may be a tendency for storms to organize
into short line segments due to flow that will be oriented parallel
to the convective axis. Wind damage will be the primary threat,
although hail and a marginal tornado threat will be possible in the
lower Great Lakes, where deep-layer shear is forecast to be the
strongest. The severe threat could persist into the early evening,
as cells move into the central Appalachians.

..Broyles/Barnes.. 05/22/2024

$$