851
ACUS48 KWNS 220857
SWOD48
SPC AC 220856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Wed May 22 2024

Valid 251200Z - 301200Z

...DISCUSSION...
...Day 4/Sat - Central/Southern Plains to Mid-MS Valley...

An upper shortwave trough over AZ/NM is forecast to spread eastward
across the central/southern Plains to the Ozarks vicinity on
Saturday. As this occurs, southwesterly mid/upper flow will
increase. Height falls will induce surface cyclogenesis over western
KS and the OK/TX Panhandles during the daytime. In response, a warm
front will lift northward across central/eastern OK/KS and much of
the Mid-MS Valley. A surface dryline will extend south from the
surface low near the OK/TX border through evening. During the
nighttime hours, the surface low is forecast to develop
east/northeast into MO while a cold front overspreads parts of the
central/southern Plains by Sunday morning.

A very moist and unstable airmass will develop over the region as
the warm front lifts north, allowing for strong destabilization. As
large-scale ascent and vertical shear increase during the
afternoon/evening, widespread thunderstorm development is expected.
Initial supercells appear possible near the dryline and surface low
over OK/KS. With time, an MCS may develop over part of the region
and spread east into AR/MO during the evening/overnight hours. All
severe hazards appear possible at this time, and higher
probabilities may be needed in subsequent outlooks as mesoscale
features become better resolved for highlighting any corridors of
greater severe risk within the broader region.

...Day 5/Sun - Ozarks to the Mid-MS/Lower OH/TN Valleys...

A synoptically concerning pattern is evident on Sunday across a
broad region of the central U.S. The upper trough from the Day 4/Sat
period will continue to shift east across the Midwest on Sunday.
This will allow strong mid/upper southwesterly flow to overspread
the region as a deepening surface low moves from MO toward Lake
Michigan. Strong to severe thunderstorms may be ongoing across parts
of MO/the Ozarks vicinity. Ahead of this activity, a rapidly
moistening boundary layer with upper 60s to low 70s F dewpoints is
expected to envelop much of the Mid-MS/OH/TN Valleys. Strong
destabilization and favorable vertical shear, along with an
eastward-progressing cold front will support both supercell storms,
and possibly a developing QLCS, capable of all hazards. While
details regarding morning convection and storm mode remain somewhat
uncertain, higher-end severe potential appears possible with this
pattern across portions of the region from midday into the nighttime
hours.

...Days 6-8/Mon-Wed...

Spread among model guidance increases quite a bit by Monday. Some
severe potential is possible anywhere from the Southern states to
the Mid-Atlantic as the upper trough lifts east/northeast. However,
details regarding storm evolution on Day 5/Sun into early Monday,
along with differing evolution of the surface pattern by various
guidance results in low predictability.

By Tuesday and Wednesday, an upper ridge is expected to move from
the western U.S. into the Plains. This should mostly shut down
severe potential west of the MS River.

..Leitman.. 05/22/2024