577
ACUS01 KWNS 262021
SWODY1
SPC AC 262020

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 PM CDT Sun May 26 2024

Valid 262000Z - 271200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTH-CENTRAL AND SOUTHEAST MISSOURI...FAR NORTHEAST
ARKANSAS...SOUTHERN ILLINOIS...FAR SOUTHWEST INDIANA...WESTERN
KENTUCKY...AND NORTHWEST TENNESSEE....

...SUMMARY...
Severe storms are expected from the Ozarks this afternoon and
evening to the Ohio and Tennessee Valley tonight. Tornadoes, some
strong to intense, and large to very large hail are the primary
threats this afternoon and evening with an evolving overnight severe
wind/embedded tornado threat tonight.

Primary focus of this outlook update was a moderate risk upgrade
from south-central Missouri into western Kentucky and northwest
Tennessee. An EML has advected across this region in the wake of
morning convection which has permitted strong heating and
destabilization. The outflow boundary and the destabilized region
north of this boundary provide a vorticity rich low-level airmass
favorable for tornadoes. Supercells are already starting to develop
in the hot and unstable airmass across southwest Missouri and will
move toward this vorticity rich airmass this evening. Additionally,
a strengthening low-level jet is expected across this area tonight
which will elongate low-level hodographs. Most members of the 18Z
and 19Z WoFS show several intense, long track supercells through
this region later this evening with increased 0-2km UH
probabilities, giving more supporting evidence for the rapidly
evolving tornado threat. Given the aforementioned factors, several
strong to intense tornadoes are possible this evening. See MCD #980
for additional information about the evolving threat in this region.


Eventually, these supercells will likely congeal into an MCS which
amid extreme instability, strong shear, and steep lapse rates, will
likely have a significant wind threat into the late evening and
early overnight hours.

In addition, added a small marginal risk across southwest South
Dakota and northern North Dakota where a few stronger storms have
developed amid weak instability and moderate shear. See MCD 982 for
additional information about this threat.

..Bentley.. 05/26/2024

.PREV DISCUSSION... /ISSUED 1140 AM CDT Sun May 26 2024/

...Ozarks/Arklatex to Ohio/Tennessee Valleys and south-central
Appalachians...
Ongoing/long-lived bowing complex, with a history of measured severe
gusts and wind damage, continues to move east across central
KY/northern TN at 16z.  The downstream environment continues to
destabilize as diurnal heating of upper 60s/near 70 def F dewpoints
continues, and this complex is expected to continue moving east
through this afternoon while maintaining a risk for damaging gusts
and embedded QLCS circulations.

In the wake of this convective system, a pronounced theta-e gradient
has become established from northern TN westward, becoming more
diffuse over southern MO, where strong heating is occurring.  Severe
thunderstorms are forecast to redevelop this afternoon across
southern MO within a strongly sheared environment characterized by
50 kts of westerly shear, and strong MLCAPE. Supercell structures
should be the dominant convective mode for several hours, with a
risk for all severe hazards including very large hail and strong
tornadoes.

The convective system may congeal with time into more of a linear
structure, with a risk for all hazards continuing into the overnight
hours within an amply-sheared and moderately unstable environment.
The Enhanced Risk has been expanded farther south over portions of
northern MS/AL/far northwest GA based on 12z HREF calibrated
guidance.

$$