Forecasters say a disturbance in the southwestern Gulf of Mexico will soon become a tropical or subtropical storm that is headed for the northern Gulf Coast.

On Thursday evening, the U.S. National Hurricane Center says the storm was about 525 miles southwest of the mouth of the Mississippi River.

It has top sustained winds of 40 mph and is moving to the northeast at 9 mph.

A tropical storm warning is in effect from the Mississippi-Alabama line to Aucilla River in Florida.