The severe weather simply refuses to quite down in the Northeast as we move into what we expect to be our third day of severe weather in 4 days. The past week has seen New England experience 4 Tornadoes in New Hampshire and Maine, though all were thankfully weak and In mostly uninhabited regions.
Currently, a shortwave trough moving through Ontario is expected to move into Southern Quebec by Monday. A mid-level disturbance is moving around the bottom of this shortwave and the disturbance will induce height falls at the 500 millibar level through Monday afternoon into Monday night, increasing the overall instability of the region. A cold front associated with the trough will move through the Great Lakes region into New England with the trailing southern portion extending through the Ohio River Valley back into Arkansas and Oklahoma.
Southwesterly flow ahead of the trough and cold front has been working to moisten the air across Pennsylvania and New York. This moist air is spreading into the Hudson River Valley and will expand across much of Western and Southern New England through Monday afternoon. Dew points are expected to climb well into the 60s at the surface with some locations approaching 70 degrees. There will be an elevated mixed layer between 700 and 500 millibars that should spread east atop this moist air which should allow for cumulonimbus clouds to build to very high heights for this area, especially across Central and Eastern New York, Northeast Pennsylvania and Western areas of New England.
There may be some limiting factors to overall destabilization if some early period convection and cloudiness occurs to limit day time heating, but moderate to high mid to upper-level cape (convective available potential energy) and strong forcing from the cold front is expected to help overcome any deficiencies that may occur from areas of limited heating. Strengthening deep layer shear is also going to be a factor and the increasing shear conditions over New York and Northern Pennsylvania as well as Western and Central New England should bring higher severe weather risks.
Strengthening westerly winds with height suggest organized storms will be possible, with some splitting of storms occurring. Damaging winds will be the primary threat though some hail cannot be ruled out.