Pickups hauling boat trailers and flatbed trucks laden with crab traps exited vulnerable, low-lying areas of southeast Louisiana on Friday as Tropical Storm Karen headed toward the northern Gulf Coast, a late-arriving worry in what had been a slow hurricane season in the U.S.

On Friday, Alabama joined Louisiana, Mississippi and Florida in declaring a state of emergency as officials and residents prepared for Karen, expected to near the central Gulf Coast on Saturday as a weak hurricane or tropical storm. The Federal Emergency Management Agency and Interior Department recalled workers, furloughed because of the government shut down, to deal with the storm and help state and local agencies.

Karen would be the second named storm of a quiet hurricane season to make landfall in the U.S. — the first since Tropical Storm Andrea hit Florida in June. Along with strong winds, the storm was forecast to produce rainfall of 1 to 3 inches through Monday night. Isolated rain totals of up to 6 inches were possible.

Late Friday, the National Hurricane Center in Miami reported that Karen was losing strength, with maximum sustained winds that had dropped to 45 mph (72 kph). Karen was located about 205 miles (330 kilometers) south-southwest of the mouth of the Mississippi River and was on the move again, heading north-northwest at 7 mph (11 kph).

Forecast tracks showed the storm possibly crossing the southeast Louisiana coast before veering eastward toward south Alabama and the Florida Panhandle. But forecasters cautioned that the track was uncertain.

"We are confident on a northeastward turn. Just not exactly sure where or when that turn will occur," Rick Knabb, director of the National Hurricane Center in Miami, said earlier Friday.

Conditions were not ripe for the storm's strengthening. A hurricane watch was dropped Friday afternoon. A tropical storm watch covered the New Orleans area as well as the area from east of the mouth of the Pearl River to Indian Pass, Fla. A tropical storm warning was in effect from Morgan City, La., to the mouth of the Pearl.

A westward tick in the earlier forecast tracks prompted officials in Plaquemines Parish, La., an area inundated last year by slow-moving Hurricane Isaac in 2012, to order mandatory evacuations, mostly on the east bank of the Mississippi River. The parish, home to oil field service businesses and fishing marinas, juts out into the Gulf of Mexico from the state's southeastern tip.

"The jog to the west has got us concerned that wind will be piling water on the east bank levees," said Guy Laigast, head of emergency operations in the parish. Overtopping was not expected, but the evacuations were ordered as a precaution, he said.

Evacuations also were ordered on Grand Isle, a barrier island community where the only route out is a single flood-prone highway, and in coastal Lafourche Parish.

Traffic at the mouth of the Mississippi River was stopped Friday morning in advance of the storm, and passengers aboard two Carnival Cruise ships bound for weekend arrivals in New Orleans were told they may not arrive until Monday.

In New Orleans, Sheriff Marlin Gusman announced that he had moved more than 400 inmates from temporary tent facilities to safer state lockups as a precaution. Mayor Mitch Landrieu said a city emergency operations center would begin around-the-clock operations Friday evening.

In the Plaquemines Parish town of Braithwaite, swamped last year by Isaac, Blake Miller and others hauled paintings and valuables to the upper floor of the plantation home he owns.

"We came out to move the antique furniture upstairs, board up the shutters, get ready. We don't know for what, we hope not much, but we have to be ready," Miller said.

"I'm not expecting another Isaac, but we could get some water, so I'm moving what I can," said Larry Bartron, a fisherman who stowed nets and fishing gear in his 26-foot fishing boat, which he planned to move inside the levee system.

Along the Mississippi, Alabama and Florida coasts, officials urged caution. Workers moved lifeguard stands to higher ground in Alabama and Florida. But there were few signs of concern among visitors to Florida's Pensacola Beach, where visitors frolicked in the surf beneath a pier and local surfer Stephen Benz took advantage of big waves.

"There is probably about 30 days a year that are really good and you really have to watch the weather, have the availability and be able to jump at a moment's notice," Benz said.

Surfers took advantage of the waves at Dauphin Island, Ala., as well. And, across Mobile Bay, pastor Chris Fowler said the surf at Orange Beach was unusually large but didn't appear to be eroding the white sand.

"Right now I'm looking at some really gargantuan waves, probably six or 7 feet high," Fowler said.

In Washington, White House spokesman Jay Carney said President Barack Obama was being updated about the storm, which put an undisclosed number of FEMA workers back to work.

"To support state and local partners, FEMA has recalled and deployed liaisons to emergency operations centers in Alabama, Florida, Louisiana and Mississippi," Carney said. "Additionally, today FEMA is deploying three incident management assistant teams recalled from furlough to the potentially affected areas to assist with the coordination of planning and response operations."

Interior's Bureau of Safety and Environmental Enforcement, which oversees offshore drilling, is providing updates on oil and gas drilling in the Gulf that has been shut-in as a result of the storm. The National Park Service and Fish and Wildlife Service were securing parks and refuges in the storm's path, officials said. The Bureau of Indian Affairs contacted the three federally recognized tribes in the storm's path to coordinate responses and assess needs. And the U.S. Geological Survey was monitoring for flood levels.

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Kevin McGill reported from New Orleans. Associated Press reporters Melissa Nelson in Pensacola, Fla.; Tony Winton in Miami; Jay Reeves in Mobile, Ala.; Michael Kunzelman in New Orleans; Alicia Caldwell and Matthew Daly in Washington; and Emily Wagster Pettus in Jackson, Miss.; contributed to this story.