Storm Prediction Center Mesoscale Discussion 221

   Mesoscale Discussion 0221
   NWS Storm Prediction Center Norman OK
   0334 PM CDT Wed Mar 11 2026

   Areas affected...portions of southern Pennsylvania...northeastern
   West Virginia...and northern Maryland

   Concerning...Tornado Watch 45...

   Valid 112034Z - 112200Z

   The severe weather threat for Tornado Watch 45 continues.

   SUMMARY...Strong to severe thunderstorms continue to pose a risk for
   damaging wind gusts, isolated large hail, and perhaps a tornado
   across Tornado Watch 45. Tornado Watch 45 has been extended eastward
   to cover the continuing severe risk, but a downstream watch appears
   unlikely at this time.

   DISCUSSION...Several low-topped supercells ongoing across portions
   of eastern Ohio into central Pennsylvania have produced sporadic
   damaging wind gusts and large hail over the past 1-2 hours and have
   occasionally shown signs of stronger low-level rotation. While
   buoyancy remains rather limited along this corridor (250-500 J/kg
   MLCAPE per latest RAP-based mesoanalysis) owing to weak mid-level
   lapse rates, strong low-level and deep-layer shear will continue to
   support an isolated severe risk for the next 1-2 hours. In the short
   term, a localized zone of marginally increased severe potential may
   exist across portions of south-central Pennsylvania, including the
   Juniata River Valley, where latest mesoanalysis suggests available
   buoyancy may be a bit higher (locally up to 1000 J/kg MLCAPE). Owing
   to recent observations, Tornado Watch 45 has been locally extended
   eastward to cover the continuing severe risk. However, a downstream
   watch appears unlikely at this time owing to increasing convective
   inhibition and more well-mixed boundary layer profiles with eastward
   extent.

   ..Chalmers/Gleason.. 03/11/2026

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

   ATTN...WFO...PHI...CTP...LWX...PBZ...

   LAT...LON   39538020 39788044 40088035 40377992 40517930 40587857
               40667763 40667703 40607654 40497628 40357614 40197616
               39967619 39607649 39447688 39287737 39237804 39227861
               39307917 39407968 39538020 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN