ACUS11 KWNS 290721
SWOMCD
SPC MCD 290720=20
ILZ000-290945-

Mesoscale Discussion 1329
NWS Storm Prediction Center Norman OK
0220 AM CDT Thu Jun 29 2023

Areas affected...Portions of central/southern IL

Concerning...Severe potential...Watch possible=20

Valid 290720Z - 290945Z

Probability of Watch Issuance...60 percent

SUMMARY...The threat for severe hail with elevated supercells may
increase over the next few hours. Watch issuance is possible.

DISCUSSION...Recent IR satellite imagery shows cooling cloud tops
with developing convection across parts of central IL. This activity
is likely being aided by low-level warm advection and related ascent
on the nose of a 25-35 kt southwesterly low-level jet that extends
across MO into central IL. A sharp instability gradient is also
present over IL based on latest mesoanalysis, extending almost due
north to south into western KY. The convection appears to be
developing along this MUCAPE gradient, and most high-resolution
guidance suggests these thunderstorms will increase in both coverage
and intensity over the next few hours.

The initial thunderstorms may be elevated supercells given a veering/strengthening wind profile with height through mid levels,
and 40-50 kt of deep-layer shear. Large hail should be the main
threat with these supercells. Some potential will also exist for
upscale growth into small bowing clusters, which would probably tend
to develop south-southeastward along the instability gradient.
Severe/damaging winds would become an increasing threat with any
cluster that develops, as a large reservoir of buoyancy and strong
DCAPE should partially offset the MLCIN present. Convective trends
will be monitored for possible watch issuance.

..Gleason/Thompson.. 06/29/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9Fyq0Jwmjv9D8eEQv87AHieUT3a6JXgjDlHVTt41c_qXRt6-2B7bbzXE83PbPfZ7AB9J7xavH= mR-blivGAVl3ZtXVDk$ for graphic product...

ATTN...WFO...PAH...LOT...ILX...LSX...

LAT...LON 38718958 39458992 40529038 41079021 41088887 40728831
40008792 39218779 38468784 38228830 38238914 38718958=20


=3D =3D =3D
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