A major winter storm is roiling the morning commute in NYC

A major winter storm slammed the New York metropolitan area on Thursday. Snow began falling overnight, with six to 12 inches expected to accumulate.

At 8 a.m., the New York City subways and buses were running without service disruptions, but the Metropolitan Transit Authority reported delays on bus routes in the city's boroughs.

The MTA also advised drivers to proceed carefully on bridges.

New Jersey Transit reported delays on commuter rails lines and informed passengers that system-wide cross-honoring of tickets would be underway for the duration of the storm.

At the airports, flights into and out of John F. Kennedy International, LaGuardia, and Newark Liberty International had been canceled ahead of the storm. According to the Federal Aviation Administration, Newark was under a ground stop, but operations were unaffected at JFK and LaGuardia.

We'll update this story throughout the morning.