NEW YORK — For all the warnings and the ominous-looking colors on the television weather maps, for all the jokes about a “snowpocalypse,” only light snow was falling when most New Yorkers turned out the lights and went to bed on Tuesday.

By the time they woke up on Wednesday, the second blustery snowstorm to sweep across the Northeast in less than a week had made its way into the New York area, and officials had closed schools, courts and the U.N. headquarters. The wind was swirling, and already slushy streets were flirting with turning slippery and treacherous. Still, in many places, it did not look all that bad.

But the storm, described by the National Weather Service as a northeaster that built up tremendous power while churning off the mid-Atlantic coast, saved its worst for a late-day punch. It delivered a messy mix — enchanting heavy snow in some places; menacing, invisible ice in others — driven by relentless wind.

“It’s the dynamics of the atmosphere,” said John Cristantello, a meteorologist with the National Weather Service. “That’s just the way it’s playing out.”

By day’s end, the storm was a midwinter diversion in Manhattan, a headache in some suburban areas and a matter of serious concern farther south. States of emergency remained in effect from Virginia to New Jersey, where Gov. Christopher Christie added seven counties in southern New Jersey to the list.

In the heavily traveled territory between New York and Washington, no one was going anywhere fast. Several major airlines, including Southwest and Continental, said they had canceled many if not all of their Wednesday flights from East Coast airports. The online service Flightstats counted more than 5,900 canceled flights nationwide on Wednesday and said 518 flights scheduled for today had already been canceled.

At the three major airports in the New York area, flights were “very minimal,” said Steve Coleman, a spokesman for the Port Authority of New York and New Jersey, which runs the airports.

On the ground, New Jersey Transit cut back on its service, combining some train runs and suspending all bus service by 7 p.m. The DeCamp line, which runs buses to towns in Essex County including Nutley, Bloomfield and Kearny, canceled departures from Manhattan at 6 p.m.

In Pennsylvania, Gov. Edward Rendell closed some highways to all but essential traffic, and the speed limit on the Pennsylvania Turnpike was cut to 45 mph. In the nation’s capital — still struggling to get going again after a brutal storm over the weekend — side streets remained unplowed and federal offices remained closed.

As if Wednesday’s storm were not enough, forecasters warned that more misery was on the way: Another storm with heavy snow could rumble into the New York area on Monday.