This is what people are forgetting with this "super" el nino....the intense warming is occurring at the end of one of the most prominent cold phases in history....lts like lamenting a SW flow slamming into a 1052mb arctic high....you can't ignore the high. The atmosphere is holding onto the last vestiges of cold ENSO for dear life and that includes a very warm western PAC.
There is always a gradient somewhere with a neg NAO/PNA pattern...the point is it wasn't a "game-over" month for the entire east coast like February. Lumping March together with February is silly.
Its both...think of it like the loaded dice analogy to describe GW in that the we have greater potential for warmer outcomes. The pattern does that with respect to snowfall, but it doesn't mean it never deviates....just like we still have colder seasons despite the background signal of GW.