After Dizzying Weather, New Yorkers Brace for Arctic Blast

It's snowing. It's raining. It's cold. It's warm. And soon it could be record-breaking cold.

Even for New Yorkers accustomed to being whipsawed by weather, the last few days have been dizzying.

And now there is the polar vortex, a deep low-pressure system bringing with it all the chills that the name implies.

The vortex itself is not forecasted to reach New York City, but it has caused a blast of arctic air to descend on the region Monday afternoon and is expected to cause temperatures to plummet overnight.

The high temperature in Central Park on Monday morning was a balmy 55 degrees. The expected temperature on Tuesday morning is 6 degrees. With wind chills, the outdoors could feel like 15 degrees below zero.

The National Weather Service does not have readily available data on large temperature swings, but experts there said that this week's weather was one of the more rapid changes they could recall.

'It is pretty rare to see a swing like this,' said Joey Picca, a meteorologist at the service.

The worst weather in New York will be in the Buffalo area and in the western part of the state, where there could be as much as three feet of snow and wind chills of 40 degrees below zero.

Gov. Andrew M. Cuomo announced on Monday afternoon that parts of the New York State Thruway in western New York would be closed because of the extreme weather. Starting at 8 p.m., all vehicles traveling westbound on the Thruway will be detoured off the roadway at Exit 50, and all eastbound traffic will be detoured off at Exit 61.

'All New Yorkers in the area should exercise extreme caution if they have to leave their homes or travel anywhere,' Mr. Cuomo said in a statement.

The most immediate concern for state and local authorities is warning those who might find themselves exposed to the cold.

The Department of Homeless Services has issued a Code Blue alert, doubling the number of people out on the street trying to reach out to those who need shelter.

The other major problem, with streets still soaking wet from the snowstorm last week and the recent rains, is likely to be ice.

There will be increased surveillance of serviceability of buses, trains and planes as well as the roads, tracks and runways they use, officials said.

'As of right now, it is fair to say that customers can expect delays, particularly on the bus side,' said John Durso, a spokesman for New Jersey Transit. 'Afford yourself ample time to get your final destinations.'

Steve Coleman, a spokesman for the Port Authority, said that even a little bit of ice could cause major problems, as was witnessed when a Delta flight slid off the runway on Sunday.

The power authorities said that large swings in temperature presented problems even without the expected deep freeze.

'A lot of times the salt that is put down during a snowstorm will melt and then run into wires' and equipment underground, said Alfonso Quiroz, a spokesman for Con Edison.

Such was the cause for a manhole fire in Brooklyn on Monday morning, which was quickly brought under control.

When the temperature drops below freezing, there is an increasing likelihood that there could be downed power lines or trees, and the utility companies have extra crews ready to be deployed.

The cold air will be accompanied by higher winds, averaging 20 to 30 miles per hour, with gusts as high as 50 m.p.h.

New York City is not expected to see temperatures drop as low as in other parts of the country, but temperatures are expected to match the record cold for Jan. 7: 6 degrees, which was set in 1896.

A polar vortex is a deep low-pressure system that stretches to the upper levels of the atmosphere and usually circulates around the polar region. The frigid air is usually penned up in the Arctic, though it has occasionally sprung free and sent tongues of cold air south. In 1985, much of the country came under a deep freeze because of a migrating polar vortex. In Central Park, the temperature dropped from a high of 34 degrees on Jan. 19 to 4 degrees on Jan. 20 and then minus 2 degrees on Jan. 21.

Some scientists have expressed concern that climate change might be changing the atmospheric forces that keep the polar vortex in check, leading to more deep freezes around the world.

Mr. Picca, the Weather Service meteorologist, said that once the cold settled in, it would take at least 24 hours to clear out.

The brief period of warm weather might have melted much of the snow on the ground, but he said that the Weather Service still expected things to get icy overnight.

'Although we did see that quick warm up, the ground temperature is still relatively cold,' he said. 'When we see the air temperature drop, there is definitely the potential for any remaining moisture out there to freeze.'