Hundreds of flights were canceled and thousands of people lost power as severe thunderstorms accompanied by heavy rain, hail and possibly a derecho windstorm swept into the U.S. Northeast.
Tornado watches were issued for parts of New York, Pennsylvania, Vermont, Connecticut and Massachusetts, according to the National Weather Service.
A line of thunderstorms had formed over western Pennsylvania and New York and was moving east, according to weather service radar at about 2:30 p.m. local time. Lightning and hail may reach New York City after 4 p.m., in time for the evening rush hour, said Tim Morrin, an agency meteorologist in Upton, New York.
"Things look on track for the potential of an outbreak that could become severe later in the afternoon," Morrin said by telephone.
A derecho may form as the systems move east. One of the fast-moving systems struck the mid-Atlantic last month, leaving 4.3 million people without power 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 flash flood watch was posted for parts of Massachusetts, Connecticut and Rhode Island, where as much as 4 inches (10 centimeters) of rain may fall quickly, the weather service said.
About 24,000 homes and businesses were without power in eastern Ohio and western Pennsylvania, utilities reported on their websites.
At least 533 flights in the U.S. were canceled as of 2:30 p.m., with the majority of them, 108, originating at LaGuardia Airport in New York, said FlightAware, a tracking company based in Houston.
If the storms develop as expected, air traffic delays will get worse, Morrin said. The area where the U.S. Storm Prediction Center predicts a moderate risk of severe weather covers the air space from Boston to Philadelphia, he said.
"It will be like a domino effect," Morrin said. "As the storms develop over Pennsylvania, that will start to close down the arrival and departure gates."
Forecasters aren't certain today's storm will meet the qualifications of a derecho, said Roger Edwards, a meteorologist at the Storm Prediction Center in Norman, Oklahoma.
"We are confident that there are going to be many wind damage reports from southern New England back into Pennsylvania and Ohio," he said. "It's just a question of whether it's organized enough that we can call it a derecho."
A derecho is defined as an event that has wind gusts of at least 58 mph and leaves a swath of damage for a minimum of 240 miles, according to the storm center's website.
A University of Iowa science professor, Gustavus Hinrichs, came up with the term in a paper published in a meteorological journal in 1888, according to the storm center. The word means "straight ahead" in Spanish and Hinrichs used it to contrast the windstorms with tornadoes that have twisting winds.
A less-intense wave of thunderstorms earlier today snarled air traffic along the East Coast from Boston to Philadelphia. Delays of more than three hours were reported at LaGuardia and in Newark, New Jersey, according to the Federal Aviation Administration.
Delays at LaGuardia, Newark and John F. Kennedy International Airport in New York were about 90 minutes at midday, the FAA said.
The storms have the potential to knock out power lines and transformers, causing widespread power outages, according to Consolidated Edison Inc.
The threat prompted New York Governor Andrew M. Cuomo to cancel events in Rochester and Syracuse and to go to New York City to help manage storm preparations, according to a statement from his office. The governor activated the State Emergency Operations Center and planned meetings with utility officials.
ConEd, which provides electricity to most of the New York City area, lifted a lockout so "necessary personnel" covered by its largest union can return and prepare for the storm, Cuomo said. For more than two weeks, the utility has blocked about 8,000 members of Local 1-2 of the Utility Workers Union of America from going to work after the two sides were unable to reach a deal on a new contract.
Tornado watches were issued for parts of New York, Pennsylvania, Vermont, Connecticut and Massachusetts, according to the National Weather Service.
A line of thunderstorms had formed over western Pennsylvania and New York and was moving east, according to weather service radar at about 2:30 p.m. local time. Lightning and hail may reach New York City after 4 p.m., in time for the evening rush hour, said Tim Morrin, an agency meteorologist in Upton, New York.
"Things look on track for the potential of an outbreak that could become severe later in the afternoon," Morrin said by telephone.
A derecho may form as the systems move east. One of the fast-moving systems struck the mid-Atlantic last month, leaving 4.3 million people without power 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 flash flood watch was posted for parts of Massachusetts, Connecticut and Rhode Island, where as much as 4 inches (10 centimeters) of rain may fall quickly, the weather service said.
About 24,000 homes and businesses were without power in eastern Ohio and western Pennsylvania, utilities reported on their websites.
At least 533 flights in the U.S. were canceled as of 2:30 p.m., with the majority of them, 108, originating at LaGuardia Airport in New York, said FlightAware, a tracking company based in Houston.
If the storms develop as expected, air traffic delays will get worse, Morrin said. The area where the U.S. Storm Prediction Center predicts a moderate risk of severe weather covers the air space from Boston to Philadelphia, he said.
"It will be like a domino effect," Morrin said. "As the storms develop over Pennsylvania, that will start to close down the arrival and departure gates."
Forecasters aren't certain today's storm will meet the qualifications of a derecho, said Roger Edwards, a meteorologist at the Storm Prediction Center in Norman, Oklahoma.
"We are confident that there are going to be many wind damage reports from southern New England back into Pennsylvania and Ohio," he said. "It's just a question of whether it's organized enough that we can call it a derecho."
A derecho is defined as an event that has wind gusts of at least 58 mph and leaves a swath of damage for a minimum of 240 miles, according to the storm center's website.
A University of Iowa science professor, Gustavus Hinrichs, came up with the term in a paper published in a meteorological journal in 1888, according to the storm center. The word means "straight ahead" in Spanish and Hinrichs used it to contrast the windstorms with tornadoes that have twisting winds.
A less-intense wave of thunderstorms earlier today snarled air traffic along the East Coast from Boston to Philadelphia. Delays of more than three hours were reported at LaGuardia and in Newark, New Jersey, according to the Federal Aviation Administration.
Delays at LaGuardia, Newark and John F. Kennedy International Airport in New York were about 90 minutes at midday, the FAA said.
The storms have the potential to knock out power lines and transformers, causing widespread power outages, according to Consolidated Edison Inc.
The threat prompted New York Governor Andrew M. Cuomo to cancel events in Rochester and Syracuse and to go to New York City to help manage storm preparations, according to a statement from his office. The governor activated the State Emergency Operations Center and planned meetings with utility officials.
ConEd, which provides electricity to most of the New York City area, lifted a lockout so "necessary personnel" covered by its largest union can return and prepare for the storm, Cuomo said. For more than two weeks, the utility has blocked about 8,000 members of Local 1-2 of the Utility Workers Union of America from going to work after the two sides were unable to reach a deal on a new contract.