Storm Prediction Center Mesoscale Discussion 1633

   Mesoscale Discussion 1633
   NWS Storm Prediction Center Norman OK
   0259 PM CDT Thu Jul 16 2026

   Areas affected...parts of southeastern Pennsylvania...southern New
   Jersey

   Concerning...Severe potential...Watch unlikely 

   Valid 161959Z - 162200Z

   Probability of Watch Issuance...20 percent

   SUMMARY...The initiation of strong thunderstorm development appears
   underway near and north through northeast of the Philadelphia area,
   with   further intensification probable through 5-7 PM EDT.  Though
   stronger storm development may remain relative isolated in nature, 
   it could be accompanied by large hail and a couple of strong
   downbursts.  It is not clear that this requires a severe weather
   watch, but trends are being monitored.

   DISCUSSION...Convergence within weak surface troughing across the
   northern Mid Atlantic coast vicinity appears weak, but has been
   sufficient to support a corridor of slowly deepening convective
   development to the north through northeast of the Philadelphia area
   the past few hours.    As a weak surface cold front slowly advances
   across this vicinity during the next couple of hours, the initiation
   of thunderstorm activity appears increasingly probable.  

   This may remain relatively isolated, but could include the evolution
   of an isolated supercell structure or two, aided by updraft inflow
   emanating from a strongly heated boundary-layer with seasonably high
   moisture content.  Beneath modestly steep mid-level lapse and 40-50
   kt westerly flow in the 700-500 mb layer, profiles appear to
   conducive the risk for large hail and a couple of strong downbursts,
   before storms spread with more favorable large-scale forcing
   offshore by early evening.

   ..Kerr/Guyer.. 07/16/2026

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

   ATTN...WFO...PHI...CTP...

   LAT...LON   40477560 40387444 39957401 39357510 40177618 40477560 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN