As Big Snowstorm Approaches New York, de Blasio Says City Is Ready Andrea Mohin/The New York Times At the Manhattanville Bus Depot, Carlos Galindo attaches bus chains in preparation for the expected snowstorm. A menacing storm that had charted a relentless course across the Midwest - leaving behind more than a foot of snow in some places, along with accidents on slippery roads and flight delays at airports - churned into the Northeast on Thursday on the timetable forecasters had predicted. The storm is expected to deliver a nighttime barrage of heavy snow and high winds to the New York region. The storm, a huge bluish blur on meteorologists" radar screens that stretched more than 700 miles from Indiana to Long Island, promised to be the first test of New York City's new mayor, Bill de Blasio. In his last job, as the city's public advocate, Mr. de Blasio was critical of the response under his predecessor, Michael R. Bloomberg, when a snowstorm hit in late 2010 and plows were slow to reach some neighborhoods, particularly in the boroughs outside Manhattan. On Thursday, less than 24 hours after being sworn in as mayor, Mr. de Blasio met with the sanitation commissioner, John J. Doherty, a temporary holdover from the Bloomberg administration, and declared that the city was "ready for whatever hits us." "We have literally all hands on deck," he said, adding that the city would face not only snow but also ice, strong winds and "a lot of different features here that we have to be ready to deal with." For starters, he urged New Yorkers to "get off the streets this evening so sanitation has the optimal conditions to work." "The one thing they need us to do," he said, "is get out of the way, so they can do the work." Forecasters warned that the snow would be heaviest overnight and would continue until midday on Long Island, which they said would face the highest accumulations. Gov. Andrew M. Cuomo of New York declared a state of emergency and ordered several major highways shut down from midnight to 5 a.m. on Friday, including the Long Island Expressway and the New York State Thruway south of Albany. Mr. Cuomo said the restrictions would also be in place on Interstate 84, which runs through Dutchess, Orange and Putnam Counties in the central Hudson Valley. Trucks and other commercial vehicles will be banned from the Interstate starting at 5 p.m., he said. The governor said that traffic on the Long Island Expressway would be blocked at the border between Queens and Nassau County, but that the Northern and Southern Parkways would stay open. "The parkways don't have the same vulnerability to blowing snow as the L.I.E.," he said in a conference call. Other state officials said drivers who ventured onto roads that had been ordered closed could face a misdemeanor charge. Tim Morrin, a meteorologist with the National Weather Service in Brookhaven, on Long Island, said he had no doubt about what kind of precipitation the storm would deliver: "It will be a snowstorm across the entire area." It had swirled and blustered across the Midwest, creating delays for airports. In Chicago, where more than seven inches of snow had fallen, more than 300 flights were canceled at O'Hare International Airport on Thursday. That was in addition to the 635 flights that were grounded there on Wednesday. But travelers" headaches were not confined to the Midwest. Nationally, more than 4,500 flights had been delayed and more than 2,000 canceled, according to Flightaware.com, a website that tracks such things. With heavy snow expected in Boston, airlines canceled all flights scheduled to leave Logan International Airport there after 9 p.m. Thursday. "Visibility is limited," said Ed Freni, the airport's director, adding that winds were expected to reach 35 miles an hour, complicating takeoffs. We're in pretty good shape right now, but we expect that to change. The storm's late-day expected arrival in the New York metropolitan area made Thursday a day of anticipation under a gloomy, gunmetal sky. Steven Yaccino contributed reporting.