Subtropical Storm Alberto is expected to be classified as a tropical storm by early Monday, according to the National Hurricane Center.
Alberto will become a tropical storm when it stops interacting with a lower pressure system, said Morgan Barry, a meteorologist with the National Weather Service in Mobile, Alabama.
"The wind speeds of tropical and subtropical systems are the same, so we are telling folks not to focus on the wording because the impacts will be the same. We are going to have coastal flooding, flash flooding and high surf," she said.
According to the National Hurricane Center, both tropical and subtropical storms have maximum sustained surface wind speeds of 39 miles per hour.
At 11 a.m. EDT Sunday, the National Hurricane Center in Miami said Alberto was about 130 miles west-southwest of Tampa, Florida, and moving north at 14 mph. The storm had top sustained winds of 50 mph.
The storm is expected to gradually strengthen and approach the north-central Gulf Coast on Monday.
The hurricane center said Sunday that a tropical storm warning was in effect from Bonita Beach, Florida, to the Mississippi-Alabama border. Isolated tornadoes were possible across the region on Sunday and Monday.
About 5 to 10 inches of rain are possible along affected areas in eastern Louisiana, Mississippi, Alabama, western Tennessee and the western Florida Panhandle. Isolated areas could see as much as 15 inches.
Contributing: Associated Press