Black cumulonimbus clouds rolled in on New York City, darkening the afternoon sky up to nearly 40,000 ft. Lightning bolts darted above Manhattan's skyscrapers. Thunder sporadically overwhelmed the city's normal noises of traffic, subways and sirens. It would be a wet but cool rush hour, a welcome break in the summer's first siege of humid heat.
At Kennedy Airport's long runways along Jamaica Bay in Queens, visibility was two miles, the ceiling 5,000 ft.both-well beyond landing and takeoff minimums. The arcs of lightning, terrifying to many air travelers, caused little concern among...