If the dry air advances south its a dryline, if the higher Tds advance north its a warm front. Chances are its a warm front. Wont have an advancing dryline moving against the mean flow (even if the downsloping from appalachians was enough to induce adiabatic warming.. but it's not). Some of those winds might have to do with flow around the appalachians which is why its so confusing. Looks like the cP air in the NE had a lot of time to modify. But yes.. that modified cP looks more like cT. Treat it as a warm front though, less dense air forcing up over stationary denser air. I bet those t-storms were quite elevated, some hail perhaps (I dont know what the vertical profile is).