Mesoscale Discussion 1864
   NWS Storm Prediction Center Norman OK
   1136 AM CDT Fri Oct 15 2021

   Areas affected...Portions of central PA

   Concerning...Severe potential...Watch unlikely 

   Valid 151636Z - 151800Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Isolated storms capable of hail and locally damaging wind
   are possible into early afternoon.

   DISCUSSION...A small thunderstorm cluster is moving across parts of
   western/central PA as of 1630Z, with the southernmost storm in the
   cluster displaying some supercell characteristics. This activity is
   likely being driven by a low-amplitude midlevel shortwave trough
   moving across the lower Great Lakes and an associated weak low-level
   warm advection regime. VWPs from PBZ and CTP show relatively weak
   low-level flow, with only modestly favorable midlevel flow noted
   from the CTP VWP, so ongoing activity may tend to weaken with time
   as it moves eastward into a generally less unstable environment, and
   watch issuance is not anticipated in the short term. 

   Later this afternoon, additional storms may develop across a larger
   portion of the region, within a gradually improving CAPE/shear
   parameter space, so some severe threat will persist across the area
   in the wake of the ongoing activity.

   ..Dean/Grams.. 10/15/2021

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

   ATTN...WFO...CTP...PBZ...

   LAT...LON   40877931 41217949 41517946 41697908 41727851 41617797
               41507777 41177765 41007767 40767785 40707796 40587832
               40587878 40877931