ACUS11 KWNS 301933
SWOMCD
SPC MCD 301932=20
KYZ000-INZ000-TNZ000-ILZ000-MOZ000-302200-

Mesoscale Discussion 1358
NWS Storm Prediction Center Norman OK
0232 PM CDT Fri Jun 30 2023

Areas affected...east-central Missouri...west-central and southern Illinois...far southwest Indiana and western Kentucky

Concerning...Severe potential...Severe Thunderstorm Watch likely=20

Valid 301932Z - 302200Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorm clusters capable of severe, damaging gusts,
and large to very large hail are expected by 23z. A severe
thunderstorm watch is likely in the next couple of hours.

DISCUSSION...An expansive cumulus field is noted to the south of an
outflow boundary across southeast MO into southern IL and western
KY/far southwest IN. Surface dewpoints across the region generally
range from 75-79 F amid 90s F temperatures. This is aiding in strong instability, with MLCAPE values from 2500-4500 J/kg. This
environment has allowed for deepening of the cumulus field over the
past hour or so, with some towering cumulus now evident in visible
across east-central MO just south of the I-70 corridor. Convective
initiation is expected by 22-23z. Initial cells are expected to
quickly cluster and propagate toward the east/southeast near the
instability gradient. This activity is expected to remain on the
southern edge of a zone of stronger effective shear, but shear will
be sufficient for storm organization. Very steep low-level lapse
rates, coupled with strong instability, will support intense
downdrafts. Thunderstorm clusters will be capable of severe gusts, a
few greater than 65 kt. While clusters are expected, the more
intense and/or discrete cores will be capable of large hail. Steep
midlevel lapse rates and somewhat elongated hodographs (per regional
forecast soundings) in the presence of large instability between
700-300 mb suggest isolated very large hail (greater than 2.5 inch
diameter) is possible. While some uncertainty in timing of
convective initiation exists due to a lack of stronger large-scale
ascent, a severe thunderstorm watch will likely be needed by around
21-22z.

..Leitman/Grams.. 06/30/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!82iKTFRp0FvmF0c4l4o92-zTJzdtLqfFtRjrXyPBS3XiCpePT1TRNNushunoTCS87-otf7www= ooBxMcDXr6jIANQhSQ$ for graphic product...

ATTN...WFO...OHX...PAH...ILX...LSX...

LAT...LON 36628791 36618849 36938947 37229011 37729099 38219143
38329149 38649152 38879142 39069095 39138992 38998909
38278742 37448720 37228721 36768747 36628791=20


=3D =3D =3D
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