July 25 (Bloomberg) -- A derecho, the kind of storm that knocked out power to millions in Washington last month, may accompany bad weather forecast for New York City and the rest of the Northeast tomorrow, the U.S. Storm Prediction Center said.
There’s a moderate chance the rare windstorm will develop in an area from Indiana to Massachusetts, the center said on its website. The region is also at risk for severe thunderstorms, hail and possible tornadoes after noon, according to John Hart, a meteorologist at the agency’s Norman, Oklahoma, offices.
“The environment is going to be favorable for considerably severe weather right across the area even if we don’t get a derecho,” Hart said by telephone.
Last month, a derecho knocked out power to at least 4.3 million people from New Jersey to North Carolina as it unleashed winds of as much as 91 miles (146 kilometers) per hour, as powerful as a Category 1 hurricane. Twenty-four deaths were linked to the storm and its aftermath, according to the Associated Press.
A derecho is defined as an event that has wind gusts of at least 58 mph and leaves a swath of damage for 240 miles, according to the storm center’s website.
A storm that swept from Chicago to Kentucky yesterday also seems to have met the definition of a derecho, Hart said. Yesterday’s storm wasn’t as intense as the one that struck the mid-Atlantic, including Washington, on June 29, he said.
Hart said derechos are hard to predict because they require that a number of atmospheric elements come together.
“There is no way to have high confidence in such a forecast,” Hart said. “We decided the risk of that scenario happening was high enough that we would highlight it.”
The area from western Ohio to southern New England will probably be in the path of severe storms tomorrow afternoon, Hart said. New York, Pittsburgh, Cleveland and Cincinnati all have a 45 percent chance of severe thunderstorms, high winds and hail.
Severe storms between the large airline hub cities of Chicago, New York and Atlanta often disrupt air travel throughout the U.S. Such fast-moving storms, which may include tornadoes, accounted for about $8.8 billion in insured losses in the U.S. in the first six months of 2012, according to the Insurance Information Institute in New York.
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