Jindal declares "state of emergency"

Debby, the first named storm of 2012 to enter the Gulf of Mexico, was centered about 200 miles east-southeast of the mouth of the Mississippi River, about 105 miles south-southwest of Apalachicola, Fla., and was moving slowly northeast at around 5 mph at 1 p.m. CDT (2 p.m. EDT).

Some slight strengthening is possible during the next 48 hours.

Louisiana Gov. Bobby Jindal on Sunday declared a state of emergency as Debby threatened to flood low-lying coastal areas. Such a declaration is a primarily bureaucratic move that makes it easier for state officials to send needed supplies and workers to disaster-stricken areas.

The NHC predicted that Debby will turn west and come ashore on the eastern Louisiana coast early Thursday as a weak Category 1 hurricane. The NHC's prior forecast predicted that Debby would continue west toward the Texas coast.

Royal Dutch Shell said it had shut production on its Auger and Enchilada/Sala production platforms in the U.S.-regulated Gulf of Mexico by Sunday as workers were evacuated ahead of Debby.

The company was also preparing operations in the central and western Gulf for further shut-ins and evacuations.

Debby has already disrupted about 8 percent of Gulf offshore oil and natural gas production.

NASA via AFP - Getty Images

This Sunday handout image provided by NASA shows a satellite view of Tropical Storm Debby as it nears the northern rim of the Gulf of Mexico.

That number could climb in coming days, with Debby expected to enter some of the most prolific production areas of the Gulf, home to 20 percent of U.S. oil production and 6 percent of natural gas output.

A tropical storm warning was issued for the Louisiana coast from the Pearl River west to Morgan City, excluding the city of New Orleans and Lake Pontchartrain. Residents were warned to expect storm conditions within 36 hours.

"Tropical storm conditions are already near or over portions of the northeast Gulf Coast and are expected to reach the remainder of the warning area tonight," the forecasters warned.

The NHC extended the storm warning east to the Mississippi-Alabama border and along Florida's northwest coast to the Suwannee River.

The combination of storm surge and high tide could cause flooding in normally dry areas near the Louisiana coast, they said.

Debby could bring 5 to 10 inches of rain to the Gulf Coast from southeast Louisiana to the central west coast of Florida, with up to 15 inches in isolated areas.

The heaviest squalls were hitting Florida's Gulf Coast, where there were unconfirmed reports that a tornado had touched down on Saturday. Several Alabama beaches were closed due to rough surf.

A tropical storm warning was issued Sunday for Alabama to the Florida Panhandle as Debby lashed parts of the Gulf Coast with wind and rain.

 The Associated Press and Reuters contributed to this story.