western/central MA down into CT stands the best bet...basically right along where the back door sets up. The biggest challenge is breaking the cap which is in place thanks to the elevated mixed-layer overhead. Typically the lift associated with back door cold fronts isn't generally strong enough to produce deep convection, however, there is some pretty impressive shear associated with the front so there stands a chance we can pop a few cells. Any storms which do develop and can become deep will likely become severe.