ABOARD A P-3 ORION OVER THE GULF OF MEXICO — From 20,000 feet, the storm was a whirl of gray padded by dark puffs, its untidy tendrils protruding over the water in every direction.

The hurricane hunters had arrived at the heart of Hurricane Barry, then a tropical storm, and the center looked unfinished, a semicircle that convulsed and heaved.

“It’s a mess,” declared Paul D. Reasor, one of the meteorological researchers who had crowded into the cockpit to take a look.

None of those aboard the plane expected to be flying now — not in July, so early in the six-month Atlantic hurricane season. But Barry had formed in unusual fashion, as a disturbance moving down from the south into the Gulf of Mexico, where warm summer waters had fueled its development.