If the low truly gets down to the 960s, 18-24” isn’t out of the question between eastern LI and Boston. No storm that deep, intensifying that fast is will be flying up the coast. The 500mb low closing off and tugging the mSLP toward the coast off the jersey shoreline (shown on the NAM and Euro the past few days) is the key to their success. If that doesn’t occur and the low skirts ENE, then you’re onto something for sure.
Looking at mid level instability charts, the dynamics in the NE NJ to BOS region are ripe for convective banding. All it takes is roughly 6 hours of 2-3” banding to get them to 12-18”. Seen it happen many times over the years living in the northeast in very similar setups. It all comes down to how quickly this storm travels from VA to south of LI.