Storm Prediction Center Mesoscale Discussion 1418

   Mesoscale Discussion 1418
   NWS Storm Prediction Center Norman OK
   0101 PM CDT Wed Jul 01 2026

   Areas affected...The northern Appalachians and portions of the New
   England region

   Concerning...Severe potential...Watch possible 

   Valid 011801Z - 012000Z

   Probability of Watch Issuance...60 percent

   SUMMARY...Watch issuance may be needed as thunderstorms develop
   within a very buoyant, but modestly sheared, environment across
   parts of the northern Appalachians/New England region.

   DISCUSSION...MLCIN has largely eroded across the greater PA/NY/NJ
   region as temperatures climb into the upper 80s/low 90s within a
   very moist air mass. Although MLCAPE has increased to around 3000
   J/kg, only a couple of deeper convective showers and at least one
   sustained thunderstorm are noted in GOES imagery within a broader
   field of otherwise shallow cumulus. This suggests that regional
   forcing for ascent remains fairly weak and localized for the time
   being.

   With the apex of the upper ridge pivoting over the region and
   relatively weak low-level flow/confluence, forcing for ascent is
   expected to remain somewhat nebulous through late afternoon.
   However, continued daytime heating should allow near-surface parcels
   to reach their convective temperatures. Localized ascent either
   within subtle confluence axes and/or along terrain features should
   promote additional isolated thunderstorm development by late mid to
   late afternoon (most likely between 19-22 UTC based on recent CAM
   solutions). Once this occurs, thunderstorm coverage may gradually
   increase as new convection develops along outflow boundaries given
   the uninhibited and strongly buoyant environment (though CAM
   guidance continues to show high variance regarding thunderstorm
   coverage though early evening). Regardless, 30-35 knot mid-level
   flow may promote some convective organization and the emergence of
   transient supercells and/or loosely organized clusters capable of
   large hail and severe gusts. Watch issuance may be needed based on
   when/where robust thunderstorm development occurs.

   ..Moore/Guyer.. 07/01/2026

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

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

   LAT...LON   41397729 41697736 41977732 42177697 43487477 43577415
               43457382 43197352 42897341 42387346 41627375 40837414
               40327453 40207511 40227571 40417620 41397729 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN