Heavy Rain as Thunderstorms in Mid-Atlantic Delay Flights

Heavy rain is forecast to wash through New York City today as severe thunderstorms and gusting winds push across the mid-Atlantic, snarling air traffic.

More than 14.9 million people are in the predicted path of today’s most severe weather, according to the U.S. Storm Prediction Center in Norman, Oklahoma. The storms will grow from a system that roared through the Midwest yesterday, touching off tornadoes, knocking power out to thousands and grounding hundreds of flights.

The Washington area will probably get the worst of it, while New York, at the fringe, may simply have heavy rain, said Tom Kines, a forecaster with AccuWeather Inc.

“D.C. stands a better chance of seeing something severe than New York City,” Kines said by telephone from State College, Pennsylvania.

As of 4:15 p.m. New York time, more than 760 flights had been canceled, with the Northeast and mid-Atlantic hardest hit, according to FlightAware, a Houston-based tracking service. US Airways Group Inc. canceled 159, while AMR Corp.’s American Airlines and American Eagle Airlines grounded 60 and United Continental Holdings Inc. scrubbed 50, spokesmen said. Southwest Airlines Co. reported “lengthy delays” in Baltimore, and expected flights at Norfolk, Virginia, and Atlanta to be affected later today.

Flights Held

Flights bound for airports in New York, Washington, Philadelphia, Baltimore and Newark, New Jersey, were being held or delayed at their points of origin, and outbound flights were being held long as 90 minutes, FlightAware said.

An area from southern New Jersey through eastern Virginia has a 45 percent chance of being raked with high winds and 30 percent chance of bearing the brunt of damaging hail storms. A tornado was confirmed near Laurel, Maryland, at 4:06 p.m., the National Weather Service said.

Flood watches and warnings reach south from Massachusetts to Virginia, while severe thunderstorm watches and warnings have been posted across West Virginia and Kentucky, according to the weather service.

“Those have some punch to them right now and I think as the afternoon wears on it will get worse,” Kines said of the thunderstorms. “We will have to worry about them in the I-95 corridor.”

Yesterday’s Storms

A line of thunderstorms yesterday touched off tornadoes, knocked out power to thousands and grounded hundreds of flights across the Midwest.

More than 66,000 customers in Chicago and northern Indiana were without power yesterday, according to utility reports. An additional 58,000 customers lost power in Pennsylvania and Ohio.

Meteorologists had feared yesterday’s thunderstorms would coalesce into a derecho, characterized by winds of at least 58 miles (93 kilometers) per hour, creating a line of damage at least 240 miles long. A derecho swept through the Midwest into the mid-Atlantic a year ago, knocking out power to 5 million people from Chicago to Washington and killing 22, according to government data.

Kines said while a derecho probably didn’t form, there was a wide area of damage from the hail, tornadoes and wind gusts the storms produced.

“Those storms that came through overnight had some punch to them,” Kines said. “I think people hear the ‘derecho’ term and they think it is the world coming to an end, but other thunderstorms can be just as bad. Don’t get hung up on the name.”

Storm Damage

Severe thunderstorms and the tornadoes that sometimes accompany them caused $15 billion in insured losses in 2012 and $25 billion in 2011, according to the Insurance Information Institute in New York.

From 1992 to 2011, thunderstorms and tornadoes accounted for the second-highest amount of catastrophic loss in the U.S., $130.2 billion, topped only by hurricanes and tropical storms with $161.3 billion, the institute said.

After the current round of rough weather passes by tomorrow, the weekend is expected to be sunny in the Northeast. Washington may have a high of 84 degrees Fahrenheit (29 Celsius) under clear skies in two days. New York is expected to have a high of 77 degrees and Boston should reach 79, according to the weather service.

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