New mesoscale discussion is out: https://www.spc.noaa.gov/products/md/2019/md0881.html
Mesoscale Discussion 0881
NWS Storm Prediction Center Norman OK
1106 AM CDT Wed May 29 2019
Areas affected...Portions of eastern OH...the northern WV
Panhandle...much of PA...and NJ
Concerning...Severe potential...Watch likely
Valid 291606Z - 291730Z
Probability of Watch Issuance...95 percent
SUMMARY...Scattered severe thunderstorms are expected to develop
this afternoon. Large hail and damaging winds should be the main
threats, but isolated tornadoes will also be possible. Watch
issuance is likely by 17Z (1 PM EDT).
DISCUSSION...A shortwave trough over central OH and Lake Erie at 16Z
will move eastward today across PA and vicinity. Isolated
thunderstorms have recently initiated across central OH and
northwestern PA in association with this feature. A belt of strong
50-65 kt mid-level westerly winds will be present across eastern OH,
much of PA, and NJ today. Long, nearly straight hodographs through
mid levels and related 40-50 kt of effective bulk shear should favor
scattered splitting supercells early this afternoon. Large hail will
probably be the initial concern with this convection, with some
increase in the damaging wind threat with time as storms potentially
congeal into one or more bowing line segments as they move
east-southeastward across PA into NJ. A marine front located over
the NYC metro area and adjacent northern NJ will likely limit the
northeastern extent of the substantial severe threat this afternoon.
In addition to the large hail and damaging wind risk, isolated
tornadoes could also occur over mainly parts of central/eastern PA
into portions of NJ to the east of a weak surface low where
low-level southwesterly winds are forecast to be somewhat stronger.
Watch issuance will likely be needed across this region by 17Z (1 PM
EDT).