Storm Prediction Center Mesoscale Discussion 448

   Mesoscale Discussion 0448
   NWS Storm Prediction Center Norman OK
   0118 PM CDT Mon Apr 14 2025

   Areas affected...Portions of the Middle/Upper Ohio River Valley to
   the Central Appalachians.

   Concerning...Severe potential...Watch likely 

   Valid 141818Z - 142015Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Severe storms capable of producing large hail and damaging
   wind gusts will spread eastward through the afternoon into the
   evening. A watch will likely be issued within an hour or two for
   parts of the area.

   DISCUSSION...Initial thunderstorms are developing across southern IN
   this afternoon, generally focused along/ahead of an eastward-moving
   cold front. Ahead of this activity, continued diurnal heating amid
   increasing boundary-layer moisture (middle/upper 50s to lower 60s
   dewpoints) will continue to erode inhibition and support additional
   storm development. Steep midlevel lapse rates (sampled by earlier
   12Z soundings) atop the destabilizing boundary layer will yield
   around 1500 J/kg MLCAPE, favoring a gradual increase in storm
   intensity through the afternoon. As 60+ kt of midlevel flow (sampled
   by upstream VWP data) overspreads the warm sector, very long/mostly
   straight hodographs (60-70 kt of effective shear) will promote
   splitting supercell structures, posing a risk of large hail and
   damaging wind gusts. Despite the expectation for an initially
   semi-discrete mode, strong outflow amid the splitting storm
   structures will favor gradual upscale growth into small lines and
   clusters with eastward extent -- with an associated increasing
   severe-wind risk. A watch will likely be issued for parts of the
   area within an hour or two.

   ..Weinman/Mosier.. 04/14/2025

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

   ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...MRX...JKL...ILN...
   LMK...

   LAT...LON   38248556 38918470 39248402 39638285 40028068 39977973
               39747915 39357876 38847859 38237864 37707920 37408001
               37228138 37038395 37138489 37338555 37818577 38248556 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN