By Jonathan Allen NEW YORK (Reuters) - The first flakes ahead of a potentially historic blizzard began swirling through New York City on Monday morning, with forecasters predicting up to 3 feet (90cm) of snow in the coming day and millions of people facing snarled transportation. The National Weather Service (NWS) issued a blizzard warning for New York City and surrounding areas beginning 1 p.m. EST on Monday, and warned of two days of winter storms across the East Coast, from Pennsylvania to Maine. "This could be the biggest snowstorm in the history of this city," New York Mayor Bill de Blasio said on Sunday. De Blasio told residents of America's financial capital and most populous city to stay off the roads and to "prepare for something worse than we have seen before." New York Governor Andrew Cuomo urged people to work from home, saying the city's bus and subway systems could be closed ahead of Monday's evening commute, along with the Metro North Railroad and the Long Island Rail Road as well as other commuter rail services.