The 12z NAM is forecasting lifted indices of +2 to -4 across SNE and into New York along with CAPE values of 250 to 750. This is obviously not the makings for widespread severe weather let alone thunderstorms, however the point is the dynamics are there for rapid cloud growth and at least isolated heavy downpours to affect the region. Right now, the best chance for thunderstorms and severe weather is in the Mid Atlantic region up to Northern New Jersey.