MIAMI (AFP) - Tropical Storm Karen, swirling offshore in the Gulf of Mexico, was on track to make landfall late Saturday in the US state of Louisiana, forecasters said.
While weakening overnight, the storm is still expected to bring rain and some coastal flooding as it moves toward Mississippi and Alabama, according to the National Hurricane Center.
At 1800 GMT, Karen was located about 205km south-southwest of Morgan City, Louisiana, packing maximum sustained winds of 64kmh.
Hurricane watches were canceled overnight, but a tropical storm warning was in effect for an area that included Morgan City, located about 112km west of New Orleans.
Battered by Hurricane Katrina in 2005, New Orleans was under a tropical storm watch.
"On the forecast track, the center of Karen will move near or over portions of southeastern Louisiana tonight and early Sunday and pass near the coast of Mississippi and Alabama Sunday and Sunday night," the Miami-based NHC said.
The storm - expected to weaken to a tropical depression on Sunday - is forecast to drop between one to three inches over the central Gulf coast and south-eastern US region through late Monday.
"Isolated storm total amounts of six inches are possible," the NHC said.
Florida Governor Rick Scott said on Saturday that 12 counties were under a local state of emergency and urged residents not to become complacent because the storm was weakening.
"As Tropical Storm Karen continues to disorganize, families should still use today as an opportunity to get ready," he said in a statement.
"Communities along the panhandle are expected to experience heavy rains, and storm surges are predicted for our coastal regions." Oil prices rose Friday on falling production as companies evacuated staff from sensitive refining and production areas along the Gulf Coast.
The main US contract, West Texas Intermediate for delivery in November, closed at US$103.84 a barrel on the New York Mercantile Exchange, up 53 cents from Thursday's closing level.
On Thursday, President Barack Obama was briefed on disaster preparations and his administration recalled emergency workers who had been told to stay home due to a government shutdown linked to a bitter budget dispute.