Mesoscale Discussion 2321

Issued

Dec 29, 2024, 1:41 PM EST (18:41 UTC)

Expired

Dec 29, 2024, 3:45 PM EST

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

The Cincinnati radar (KILN), 133 km from the middle of the area, began a volume at 18:42 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

110 
ACUS11 KWNS 291842
SWOMCD
SPC MCD 291841 
OHZ000-INZ000-292045-

Mesoscale Discussion 2321
NWS Storm Prediction Center Norman OK
1241 PM CST Sun Dec 29 2024

Areas affected...portions of far eastern IN and central OH

Concerning...Severe potential...Watch unlikely 

Valid 291841Z - 292045Z

Probability of Watch Issuance...20 percent

SUMMARY...Low-topped thunderstorms may pose a risk for occasional
damaging gusts and perhaps a brief tornado this afternoon. Weak
buoyancy suggests the threat is limited and a WW is unlikely.

DISCUSSION...As of 1830 UTC, afternoon analysis showed an impressive
negative tilt, 500 mb trough centered over IN and western OH. Near
the center of the upper trough, cold 500 mb temperatures (-20C to
-23C) were advecting over the northern fringes of returning surface
moisture across the upper OH Valley. East of a deepening sub 1000 mb
surface cyclone, differential temperature advection and strong DPVA
were aiding in steepening low and mid-level lapse rates to 6-7 C/km.
In combination with marginal surface moisture (50s F dewpoints) weak
buoyancy (100-400 J/kg MUCAPE) has developed, and is supporting a
band of low-topped convective showers/weak thunderstorms across
southeastern IN into southern OH/KY.

Despite meager buoyancy, very strong mid and low-level wind fields
are present, and should continue to intensify as the surface low and
upper trough deepen. Deep-layer shear in excess of 70 kt (ILN VAD)
will allow for some organization of the low-topped storms into a
broken band or QLCS structure. Downward mixing of the stronger
mid-level flow within the convective line could support sporadic
damaging gusts across parts of central OH this afternoon.
Additionally, the distribution of the weak buoyancy concentrated
near the surface, along with strong shear and ample vertical
voritcity suggest a brief tornado is possible within the stronger
convective elements.

The primary limiting factor remains the marginal buoyancy and
limited moisture. Dense cloud cover is in place over much of
north-central and eastern OH/PA which will further limit seasonally
muted diurnal heating. Thus, while sporadic gusts and perhaps a
brief tornado cannot be ruled out a WW appears unlikely.

..Lyons/Hart.. 12/29/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PBZ...RLX...CLE...ILN...IWX...IND...

LAT...LON   40808131 39848122 39038247 39138404 39598503 40228505
            40668437 41188295 41438199 41368173 40808131

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.