ACUS11 KWNS 251922
SWOMCD
SPC MCD 251922=20
KYZ000-INZ000-252045-

Mesoscale Discussion 1256
NWS Storm Prediction Center Norman OK
0222 PM CDT Sun Jun 25 2023

Areas affected...Portions of southern IN and southern/central KY

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

Valid 251922Z - 252045Z

Probability of Watch Issuance...80 percent

SUMMARY...The threat for tornadoes, very large hail, and damaging
winds should increase this afternoon. Tornado watch issuance will
likely be needed in the next couple of hours.

DISCUSSION...Recent attempts at convective initiation have been
noted across parts of southern IL along and just ahead of a surface
cold front. Latest visible satellite imagery also shows an outflow
boundary from prior convection arcing northward from middle TN into
western KY and far southwestern IN, intersecting the cold front in
far southeastern IL. Low-level winds to the west of the outflow
boundary have generally veered to west-southwesterly. But surface
and boundary-layer winds along/east of this boundary are backed to south-southeasterly.

A rather unstable and strongly sheared environment is present across
southern IN into western/central KY ahead of the cold front, and
near the outflow boundary. Steep mid-level lapse rates and strong
diurnal heating of a very moist low-level airmass are contributing
to 1500-2500+ J/kg of MLCAPE this afternoon. A 50+ kt mid-level
westerly jet and veering wind profile with height through mid levels
is supporting 45-55+ kt of deep-layer shear. Supercells are expected
to continue forming with southward extent along the cold front into southwestern IN. Very large hail will be a threat with this
initially discrete development.

The tornado threat is less clear in the short term due to weak
low-level winds. But, backed southerly winds to the east of the
outflow boundary along with gradually increasing winds associated
with an approaching low-level jet should support locally greater 0-1
km SRH, and some threat for tornadoes, as convection spreads
eastward into central KY later this afternoon and early evening.
Damaging winds will also be possible with any upscale growth into
small clusters that can occur. Given the potential for robust
supercells to develop along/near the OH River in the next 1-2 hours,
Tornado Watch issuance will likely be needed.

..Gleason/Grams.. 06/25/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4nBhxPJyodAf-8E0J-DCqBMQBxg7zsL2RRhp-vtfoIxZkgYmTzlJXX35QQCdK-xkSBIrxQNOD= IomuyAsRcDGOuR-jeg$ for graphic product...

ATTN...WFO...LMK...PAH...

LAT...LON 37958793 38328757 38708546 38128502 37328545 36808631
36788723 37298795 37958793=20


=3D =3D =3D
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