(CNN) -- Regardless of whether Tropical Storm Karen becomes a hurricane, a soggy weekend is in store for parts of the U.S. Gulf Coast.

The storm, expected to near land between southeastern Louisiana and the Florida Panhandle on Saturday night or Sunday morning, weakened Friday morning as it churned in the central Gulf of Mexico, the National Hurricane Center said.

Karen's maximum sustained winds dropped to about 50 mph -- down from 60 mph three hours earlier -- as it was centered about 250 miles south-southwest of the Mississippi River's mouth about 11 a.m. Friday.

The storm could strengthen as it crosses warm waters, raising the possibility that it could get the 74-mph winds it needs to be a category 1 hurricane, forecasters said.

But the hurricane center indicated Friday morning that a hurricane watch -- currently in effect from Grand Isle, Louisiana, to west of Destin, Florida -- could be changed to a tropical storm watch or warning later in the day.

A tropical storm warning is in effect from Morgan City, Louisiana, to the mouth of the Pearl River on the Louisiana-Mississippi line.

3 to 6 inches of rain

The storm is expected to drop 3 to 6 inches of rain over parts of the central and eastern Gulf Coast through Sunday night, mainly near and to the east of the storm's center, the hurricane center said. Isolated storm total amounts of 10 inches are possible.

Storm surges also are a concern. If peak surges coincide with high tide, water could reach 3 to 5 feet above ground from the mouth of the Mississippi River in Louisiana to Alabama's Mobile Bay, the center said.

"The combination of storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters," the center said.

The hurricane center's tracking map shows that the storm could make two landfalls: once over the Louisiana barrier islands Saturday night and again over the Florida Panhandle on Sunday morning.

Back to work at FEMA

The storm prompted the Federal Emergency Management Agency to recall some of its workers furloughed during the government shutdown. The agency also reactivated its Hurricane Liaison Team at the National Hurricane Center in Miami. FEMA officials in the Atlanta and Denton, Texas, offices are monitoring Karen.

"At all times, FEMA maintains commodities, including millions of liters of water, millions of meals and hundreds of thousands of blankets, strategically located at distribution centers throughout the United States, including in the Gulf Coast region, that are available to state and local partners if needed and requested," the agency said in a statement.

The hurricane center said it, too, would be unaffected by the government shutdown as Karen approaches.

"The National Hurricane Center is fully operational ... and has all of its resources available to it," spokesman Dennis Feltgen said in an e-mail. "The government shutdown will not inhibit NHC from providing its mission."

Storm preparations

Louisiana Gov. Bobby Jindal declared a statewide state of emergency. Florida Gov. Rick Scott declared a state of emergency in 18 counties.

New Orleans officials released a statement asking residents to "monitor weather conditions and stay alert." The city is included in the tropical storm watch area.

Karen formed between Cuba and Mexico's Yucatan Peninsula.

The storm was moving north-northwest at 10 mph Friday morning, the hurricane center said. It is expected to turn north by early Saturday and then northeast on Sunday, the center said.