Drier air limits chance that tropical storm will form

Tropical Depression 4 formed Wednesday in the Atlantic Ocean east of the Caribbean Sea, and it is on a slow and uncertain path that could mean an impact on the East Coast of the United States next week.

"The system is surrounded by dry air, and that tends to limit development prospects," WRAL meteorologist Nate Johnson said.

The chance the system develops into a tropical storm – meaning winds accelerate to a maximum of up to 73 mph – is very low, but it is not outside the realm of possibility. Should it become a named storm, it would be Don.

By Thursday morning, the storm was moving northwest at just 17 mph, but it was expected to gain speed.

Given the system's speed and trajectory, it could be the middle of next week before any effects are felt along the coast, Johnson said.