Authorities on the Gulf Coast told residents Thursday to brace for a hit from Tropical Storm Karen, set to become the first named system to strike the United States this year.

President Barack Obama was briefed on disaster preparations, and his administration recalled hurricane emergency workers who had been furloughed due to a government shutdown.

A hurricane watch was in effect from Grand Isle, Louisiana, eastward to Indian Pass, Florida, forecasters said.

The city of New Orleans -- devastated by Hurricane Katrina in 2005 -- was under a tropical storm watch, according to the National Hurricane Center.

"Gulf Coast residents in potentially impacted areas should take steps now to be prepared and follow the direction of local officials," said Craig Fugate, head of the Federal Emergency Management Agency.

Households should stock up on essentials such as water, non-perishable food and medication, as well as cell phone chargers and extra batteries for radios and flashlights, FEMA said.

Obama directed his team to ensure that federal resources and manpower needed to help state and local officials was in place, his spokesman Jay Carney said.

"The president directed his team to keep him apprised as weather conditions change and as preparations continue," he said.

"He urged residents in potentially affected areas to follow the instructions of local response and law enforcement officials."

Karen -- expected to be at or near hurricane strength on Friday -- could approach land within the hurricane watch area on Saturday, the Miami-based forecasters said.

At 1800 GMT, Karen was about 430 miles (695 kilometers) south of the mouth of the Mississippi River, packing top winds near 65 miles per hour (100 kilometers per hour).

The storm, situated in the southeastern part of the Gulf, was moving north-northwestward at 12 miles per hour.

"Some strengthening is possible in the next day or so and Karen is expected to approach the coast within the hurricane watch area on Saturday," the NHC said.

Due to a government shutdown sparked by a bitter budget impasse in Congress, some 800,000 federal workers from a wide swath of agencies were told to stay home earlier this week.

Karen was expected to trigger heavy rains over parts of western Cuba and the northeastern Yucatan Peninsula over the next day or so.