Louisiana's governor declared a state of emergency Sunday as Tropical Storm Debby approached, citing "the imminent threat" of heavy rainfall and flooding.
Debby was unleashing high winds and torrential rain Sunday along portions of the northeast Gulf Coast as it meandered offshore, forecasters said.
But those in Louisiana stepped up preparedness efforts amid concern over a forecast track showing Debby could make landfall along its coast, although meteorologists noted the storm's path is still uncertain.
Gov. Bobby Jindal's declaration authorizes the governor's Office of Homeland Security and Emergency Preparedness to undertake any activity its director deems necessary or appropriate.
In Plaquemines Parish, the state's southernmost parish, authorities were utilizing baskets and tubes in an effort to keep Highway 23 -- the parish's main evacuation and emergency route -- free of water should the 4-foot levees be topped, said Billy Nungesser, parish president.
"We want to be ahead of that as a precautionary measure," Nungesser said. The area is forecast to receive a storm surge of 2 to 4 feet, he said -- "with a direct hit, if it goes up a little bit more, we'll have those levees topped."
Officials were also sandbagging the levees as an additional precaution, he said.
As of 10 a.m. (11 a.m. ET), the center of Debby was about 190 miles east-southeast of the mouth of the Mississippi River and about 140 miles south-southwest of Apalachicola, Florida, according to the National Hurricane Center in Miami. Packing sustained winds of 60 mph, the storm was moving northeast at about 6 mph.
A tropical storm warning was in effect for coastal Louisiana from the mouth of the Pearl River westward to Morgan City, the weather agency said, not including New Orleans or Lake Pontchartrain.
A second warning was extended eastward Sunday from the Mississippi-Alabama border eastward to Florida's Suwannee River, and a tropical storm watch was issued for an area south of the Suwannee River to Anclote Key, Florida.
Some slight strengthening is possible within the next 48 hours, the hurricane center said.
A tropical storm warning means that tropical storm conditions, including sustained winds of 39 to 73 mph, are expected in the warning area within 36 hours, said CNN meteorologist Bonnie Schneider.
"If you are under this warning, take your precautions now," she said. "Tie down or bring inside any furniture, toys or decorations you keep outside. They may blow about in strong winds and cause damage or injuries.
"If you are in a low-lying area at risk for flooding, know the best route to higher ground where you live," Schneider said, and stay abreast of local weather warnings.
A tropical storm watch means tropical storm conditions, including winds of at least 39 mph, are possible within the watch area within 12 to 24 hours, the hurricane center said.
The forecast track shows Debby strengthening into a hurricane early Wednesday off the coast near the Mississippi-Alabama state line, then coming ashore in coastal Louisiana early Thursday.
However, uncertainty remains about Debby's track, said Dave Hennen, CNN senior meteorologist, and computer models show a wide variety of places where the storm may make landfall, from the upper Texas coast to the Florida panhandle.
"We must be ready to make a change of the forecast track at any time," hurricane center forecasters said.
If Debby does continue toward Louisiana, warnings including New Orleans may be issued, Hennen said.
Tropical storm-force winds extend outward up to 200 miles from Debby's center, according to the hurricane center.
"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 by tonight," forecasters said Sunday.
Bald Point, Florida, about 45 miles south of Tallahassee, reported sustained winds of 37 mph Sunday morning with gusts to 43 mph, the hurricane center said.
"The combination of a storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters," the hurricane center said. Floodwaters in parts of coastal Mississippi and Louisiana could reach 2 to 4 feet deep; in Florida's Apalachee Bay, waters could reach 3 to 5 feet.
Debby is also expected to dump 3 to 6 inches of rain from southern Louisiana to the Florida panhandle, with up 10 inches in isolated areas, the weather agency said.
In addition, "isolated tornadoes are possible" over parts of west-central and southwestern Florida on Sunday.
Some adventure-seekers took advantage of high winds and large waves along the shore as Debby approached. A CNN iReporter sent a picture Sunday of a kite surfer on Grayton Beach, Florida.
Nine oil and gas production platforms have been evacuated, equivalent to 1.5% of the 596 manned platforms in the Gulf of Mexico, the federal government said Saturday. One of 70 rigs was evacuated.
St. Mary Parish planned Monday to place warning signs at two communities built at sea level, said Duval Arthur, director of emergency preparedness. "We're anticipating a 3- to 4-foot high tide. Water would be over the road in those areas."