508
ACUS48 KWNS 230859
SWOD48
SPC AC 230857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Thu May 23 2024

Valid 261200Z - 311200Z

...DISCUSSION...
...Day 4/Sun - Ozarks, Mid-MS/Lower OH/TN Valleys...

A regional severe weather episode is expected on Day 4/Sunday.
Significant severe thunderstorms capable of all hazards will be
possible.

An upper trough will overspread the region, resulting in a corridor
of strong southwesterly mid/upper flow overlapping a very moist and
strongly unstable airmass. Forecast guidance depicts a 700 mb
southwesterly jet around 45-60 kt over the Mid-MS/Lower OH Valley
vicinity. Meanwhile, a surface low near northeast KS/northwest MO at
the beginning of the period will deepen as it lifts northeast toward
Lake Michigan through the evening. A cold front will develop east
across the region from late afternoon into the overnight hours.
Ahead of the front, mid/upper 60s F dewpoints are expected. Steep
midlevel lapse rates atop this moist boundary layer will support
strong destabilization.

Convection will likely be ongoing Sunday morning across parts of the
Mid-MS/Lower MO Valley. The evolution of this activity is a bit
uncertain, but may continue to develop east along a warm front
draped across northern IL/IN. Additional convection is expected
across the warm sector from southeast MO/northwest AR eastward into
TN/KY. While storm mode/evolution remains a bit uncertain at this
time (may be a mix of supercells and more linear convection),
supercell wind profiles coupled with favorable thermodynamics will
support all-hazards severe potential across a broad area during the
day and into the nighttime hours.

...Day 5/Mon - Mid-Atlantic to the Southeast...

Spread among forecast guidance increases considerably on Monday and
various models evolve the central U.S. upper trough quite a bit
differently. If a more progressive system prevails, favorable
vertical shear and large-scale ascent will overspread parts of the
Mid-Atlantic vicinity (decreasing with southward extent into the
Southeast). Severe-storm potential may develop ahead of an
east/southeastward-advancing cold front if this scenario unfolds.
However, uncertainty precludes introduction of 15 percent severe
probabilities at this time.

...Days 6-8/Tue-Thu...

Forecast spread increases further late in the period. Overall severe
potential appears to wane for much of the CONUS during this time,
but predictability is low.

..Leitman.. 05/23/2024