Olga had maximum sustained winds of 50 mph (80 kph) and was centered about 275 miles (443 kilometers) south-southeast of Lake Charles, Louisiana on Friday night. It was moving north-northeast at 17 mph (27 kph).
It's expected to weaken as it moves over land on Saturday morning.
A tornado has been reported on the ground in southwestern Alabama.
The National Weather Service on Friday afternoon issued a tornado warning for Mobile County.
The National Weather Service in Mobile tweeted that a there was a large and dangerous" tornado on the ground near Semmes, Alabama and people should seek shelter immediately. A second possible tornado was in Washington County.
There were no immediate reports of injuries.
WKRG reported that viewers sent in video of what appeared to be a large tornado on the ground.
Forecasters say Tropical Storm Olga has formed in the Gulf of Mexico while Tropical Storm Pablo has formed in the northeast Atlantic.
On Friday afternoon, the National Hurricane Center said the storm is expected to soon merge with a cold front and become a post-tropical low with gale force winds.
The storm has maximum sustained winds of 40 mph (64 kph) and was centered about 260 miles (418 kilometers) south of Lake Charles, Louisiana. It's moving north-northeast at 18 mph (29 kph).
Forecasters expect the storm's center to move over the northern Gulf coast late Friday or early Saturday.
No coastal tropical cyclone watches or warnings are currently in effect.
Officials say Tropical Storm Pablo is a small storm that is moving east-southeast. There are no coastal tropical cyclone watches or warnings in effect.
Parts of the drought-parched South are under flood watches and warnings with forecasters saying as much as 10 inches of rain could fall.
The National Weather service says an advancing cold front will collide with a weather disturbance that became a tropical depression early Friday in the Gulf of Mexico.
The National Hurricane Center said the storm's center was 320 miles (515 kilometers) south-southwest of Lake Charles, Louisiana. It had maximum sustained winds of 35 mph (55 kph).
Forecasters say coastal Louisiana could receive as much as 10 inches (25 centimeters) of rain Friday and Saturday; 6 inches (15 centimeters) was possible across a wide section of Mississippi.
Rainfall totals ranging from 1 to 4 inches (2.5 to 10 centimeters) are possible from Alabama to South Carolina.