Heavy rain delaying flights across eastern U.S.
Four inches of rain could hit New York City over 24 hours.
Northwest travel guides
Heavy rain and air traffic delays spread across the U.S. East Coast from a storm that lashed the South and Midwest with tornadoes and flooding.
New York City, under a flood watch from Wednesday afternoon until noon Thursday, may receive as much as 4 inches of rain, according to the National Weather Service.
The path of the storm front will cause air traffic delays and some cancellations in the eastern U.S., said Gary Best, a meteorologist with Hometown Forecast Services in New Hampshire.
Across the U.S., 668 flights were scrubbed as of 3:54 p.m. (EDT) with Philadelphia International Airport most affected, said FlightAware, a Houston-based airline tracking company.