068
ACUS11 KWNS 212234
SWOMCD
SPC MCD 212233
ILZ000-MOZ000-ARZ000-OKZ000-KSZ000-220030-

Mesoscale Discussion 0880
NWS Storm Prediction Center Norman OK
0533 PM CDT Tue May 21 2024

Areas affected...parts of west central Illinois and northeastern
Missouri southwestward into northeastern Oklahoma

Concerning...Tornado Watch 278...

Valid 212233Z - 220030Z

The severe weather threat for Tornado Watch 278 continues.

SUMMARY...Supercell development will persist in narrow
east-southeastward pre-frontal corridor, with some potential the
continued evolution of an organizing squall line through 7-9 PM CDT.
 Stronger storms will continue to pose a risk for large hail,
locally damaging wind gusts and a couple of tornadoes.

DISCUSSION...Thunderstorm development persists just east of the
dryline as a southeastward advancing cold front overtakes it.
Activity has evolved into a mix of linear and discrete supercell
cell structures, which will tend to slowly shift southeastward as
the deep cyclone continues migrating northeastward through the Upper
Midwest, and flow to its south veers to a more prominent westerly
component and begins to weaken.

Convection is still embedded within strong southwesterly deep-layer
mean flow in excess of 50 kt, which is supporting fast northeasterly
cell motion, but at least somewhat drier and less unstable
boundary-layer air lingers across south central through east central
Missouri and west central Illinois.  Stronger convective development
probably will remain focused in the rather narrow corridor of better
pre-frontal low-level, which guidance does suggest will tend to
shift eastward ahead of the front toward the middle Mississippi
Valley through 01-03Z.

Within this narrow corridor, large CAPE and strong shear will
maintain a risk for severe hail/wind and potential for a couple of
tornadoes several more hours

..Kerr.. 05/21/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ILX...LSX...DVN...SGF...EAX...TSA...

LAT...LON   40539230 39949043 36969267 36199384 35839584 37409421
            39489283 40539230