ACUS11 KWNS 191925
SWOMCD
SPC MCD 191925=20
INZ000-KYZ000-TNZ000-ILZ000-192130-

Mesoscale Discussion 0245
NWS Storm Prediction Center Norman OK
0225 PM CDT Wed Mar 19 2025

Areas affected...parts of southern Illinois and Indiana...western
Kentucky

Concerning...Severe potential...Watch possible

Valid 191925Z - 192130Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorm development east of the Mississippi River,
into areas south of the Ohio River, appears increasingly possible by
5-7 PM CDT, if not a bit earlier.  This may include the evolution of
a broken line with embedded supercells, posing at least the risk for
severe hail and wind.

DISCUSSION...From around the Greater St. Louis area southward,
convective development along the dryline still appears suppressed by
mid-level subsidence and warming to the east and south of the
intense cyclonic mid-level jet nosing through the middle Mississippi
Valley.  However, better low-level moisture return (characterized by
mid 50s F surface dew points) is ongoing across the Missouri
Bootheel and adjacent portions of western Kentucky through southern
Illinois.  As this continues, coincident with the eastward
progression of the mid-level trough, it appears that mid-level
forcing for ascent and cooling aloft may gradually overcome
inhibition and support increasing thunderstorm development, perhaps
into areas south of the Ohio River by early evening.

Rapid Refresh forecast soundings indicate considerable strengthening
and enlargement of the low-level hodographs around this same time,
though perhaps with a tendency for the hodographs to trend more
linear as thunderstorms finally initiate with the removal of the
mid-level inhibition.  Regardless, strong deep-layer shear will be
supportive of organized convection, including supercells, with
potential to produce at least severe hail and wind.

..Kerr/Leitman.. 03/19/2025

ATTN...WFO...LMK...OHX...IND...PAH...

LAT...LON   36788895 38078861 38888669 38518637 37378714 36618804
            36788895=20

ACUS11 KWNS 192037
SWOMCD
SPC MCD 192037=20
INZ000-ILZ000-192230-

Mesoscale Discussion 0246
NWS Storm Prediction Center Norman OK
0337 PM CDT Wed Mar 19 2025

Areas affected...eastern Illinois into far western Indiana

Concerning...Tornado Watch 57...

Valid 192037Z - 192230Z

The severe weather threat for Tornado Watch 57 continues.

SUMMARY...Strong to severe thunderstorm development is likely to
continue to increase during the next few hours, including the
potential for supercells with tornadoes across much of east central
Illinois into the Indiana state border vicinity through 5-7 PM  CDT.

DISCUSSION...Aided by stronger mid-level forcing for ascent and
cooling, within the exit region of the intense mid-level jet nosing
through the middle Mississippi Valley, an intensifying and evolving
broken line of thunderstorms appears likely to spread across and
east of the Interstate 55 corridor of central Illinois through
21-22Z.  This is where 20Z surface observations indicate that rapid
(2-hourly in excess of 4 mb) surface pressure falls are maximized,
and lower 50s surface dew points are being maintained with perhaps
some further increase ongoing farther east, into the vicinity of the
Indiana state border vicinity.

More discrete thunderstorms are now initiating farther south,
between Taylorville and Salem, which are likely to continue rapidly
moving north-northeastward within 50-60 kt south-southwesterly
deep-layer mean flow.  Rapid Refresh forecast soundings continue to
suggest that this will coincide with enlarging clockwise-curved
low-level hodographs near/east of Kankakee, Champaign, Decatur
vicinities, where south to southwesterly flow is forecast to
intensify within the 850-700 mb layer through 22-00Z.  And it still
appears the low-level thermodynamic profiles may become conducive to
supercell tornadoes, perhaps including a strong tornado or two.

..Kerr.. 03/19/2025

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

LAT...LON   41618831 41418744 38798741 38288815 38388861 40008935
            41618831

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