From the SPC
...Northeast States...
Water vapor imagery shows a broad upper trough digging across the
Great Lakes region, with the associated cold front sweeping across
southeast Ontario and OH. Mostly clear skies and dewpoints in the
60s to lower 70s ahead of the front, coupled with steep midlevel
lapse rates shown on 12z raobs and model forecast soundings will
yield a moderately unstable air mass by early afternoon (MLCAPE over
2000 J/kg). It appears thunderstorms will develop by early
afternoon along the front - and in the free warm sector to the east.
Vertical shear will be sufficient for a mix of multicell and
occasional supercell structures, capable of damaging winds and large
hail. Low level shear is strongest over Quebec, but may be
sufficient over parts of VT/NY for an isolated tornado or two as
well. Activity will sweep eastward across the ENH risk area through
the early evening, before weakening as it approaches cooler
marine-influenced air mass over eastern New England and NJ.