Storm Prediction Center Mesoscale Discussion 2321

   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