Mesoscale Discussion 1870
   NWS Storm Prediction Center Norman OK
   1006 AM CDT Sat Oct 16 2021

   Areas affected...Central/Eastern PA...South-Central NY

   Concerning...Severe potential...Watch possible 

   Valid 161506Z - 161700Z

   Probability of Watch Issuance...60 percent

   SUMMARY...A narrow line of stronger storms is expected to move
   northeastward into more of eastern PA and south-central NY over the
   next few hours. Convective trends will be monitored for possible
   watch issuance.

   DISCUSSION...Recent radar trends show increasing reflectivity within
   the line of showers and thunderstorms just ahead of the front in
   central PA. Recent lightning data shows an increasing trend in
   flashes within this line as well. This matches forecast expectations
   with storms expected to gradual strengthen amid continued lift along
   the front, increasing large-scale forcing for ascent, and modest
   diurnal destabilization. 

   Low to mid-level flow is also strengthening across the region, shown
   well by the BGM VAD, which recently sampled 45-50 kt at 1 km AGL
   increasing to 60 kt between 2-3 km AGL. The resulting vertical
   profile had 0-1 km bulk shear around 35 kt and 0-1 km storm-relative
   helicity near 250 m2/s2. 

   The resulting combination of ascent, modest buoyancy, and strong
   vertical shear is forecast to result in a narrow line of deeper
   convection capable of producing damaging wind gusts and maybe even a
   brief embedded tornado or two as it moves northeastward.

   ..Mosier/Grams.. 10/16/2021

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

   ATTN...WFO...ALY...PHI...BGM...CTP...

   LAT...LON   41547731 42467639 43167557 42797445 41897459 39917606
               40107789 41547731