ACUS11 KWNS 281918
SWOMCD
SPC MCD 281918=20
INZ000-ILZ000-MOZ000-282115-

Mesoscale Discussion 2281
NWS Storm Prediction Center Norman OK
0118 PM CST Sun Dec 28 2025

Areas affected...Far eastern Missouri...central and southern
Illinois...and western Indiana

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

Valid 281918Z - 282115Z

Probability of Watch Issuance...60 percent

SUMMARY...A band of storms is expected to form along the cold front
by mid afternoon in Illinois and spread eastward through late
evening into Indiana. Occasional wind damage and a couple of
tornadoes will be the main threats, and a watch is possible by
20-21z.

DISCUSSION...A surface cyclone is in the early stages of deepening
along a baroclinic zone across northern IL, downstream from an
amplifying midlevel trough and associated 100+ kt midlevel jet.=20
Within the warm sector of the cyclone, visible satellite imagery
shows some cloud breaks from MO into central IL, where surface
temperatures have warmed to 68+ F with dewpoints in the low 60s.=20 Surface-based CAPE has increased to 500-1000 J/kg as convective
inhibition weakens immediately ahead of the front. Shallow
convection is ongoing in the zone of ascent along the front, and the
threat for thunderstorms will increase through late afternoon as the
front interacts with the moist/weakly unstable boundary layer into
IL.

Strong deep-layer shear/long hodographs favor supercells. Still,
relatively weak buoyancy, linear forcing for ascent and fairly fast
frontal movement favor a more linear storm mode tied closely to the
frontal circulation. Thus, a mixed convective mode is probable,
with damaging gusts the main threat given roughly 50 kt flow in the
lowest 1-2 km above ground level. A couple of tornadoes may also
occur with any sustained supercells and/or embedded circulations
within line segments. A watch may need to be considered by 20-21z.

..Thompson/Gleason.. 12/28/2025

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!5KVJ_7w_RBwKx-5veHAywKVwnBYou8SOxTgUsbH4PdEli6dIIKbOe-17J3IH5sAccD9PYaLET= ZPVkbbN6CdgsY6q3qQ$ for graphic product...

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

LAT...LON 38998743 37448896 37519006 38929046 39679034 40678945
41028902 41118844 41258684 41068649 40188648 38998743=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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