NEW ORLEANS -- New Orleans, and states from Louisiana to Florida, braced Friday as forecasters predicted Tropical Storm Nate would pound the Gulf Coast this weekend as a hurricane.
The center of the storm was expected to pass late Saturday or early Sunday about 50 miles east of New Orleans, which was devastated 12 years ago by Hurricane Katrina, according to the National Hurricane Center. It would be the third hurricane, after Harvey and Irma, to hit the US mainland in six weeks.
A tropical storm warning was issued late Friday morning for New Orleans and Lake Pontchartrain, west to Morgan City, Louisiana, the hurricane center said, while a hurricane warning was issued from Grand Isle, Louisiana, to the Alabama-Florida border.
A storm surge warning was put in place from Morgan City to the Alabama-Florida line, as well as along the northern and western shores of Lake Pontchartrain.
Nate killed at least 21 people as it passed Thursday over Costa Rica, Nicaragua and Honduras, where it caused widespread flash flooding and mudslides, officials said.
Strengthening over the northwestern Caribbean Sea, Nate was forecast to gain force as it approaches the Yucatan Peninsula later Friday and strengthen into a Category 1 hurricane by the time it makes landfall along the Gulf Coast, the hurricane center said.
Nate packed maximum sustained winds of 50 mph Friday morning and was moving north-northwest at 21 mph, the hurricane center said.
New Orleans gearing up
New Orleans Mayor Mitch Landrieu declared a state of emergency Thursday and advised residents to stay put over the weekend.
"There is no need to panic. Be ready and prepare. Get a plan. Prepare to protect your personal property," Landrieu tweeted.
Gov. John Bel Edwards declared a state of emergency for all of Louisiana. The storm will "make landfall in the close vicinity of New Orleans," the proclamation noted, adding that six parishes have declared emergencies and others would do so soon.
New Orleans, much of which lies below sea level, was gearing up for a hit, and Landrieu urged people who live "outside the city's levee protection system or in low-lying area" to seek higher ground.
Residents have been wary since the city's unique drainage system experienced critical deficiencies during heavy summer rainstorms, leading to the flooding of several hundred properties.
Of the city's 120 main drainage pumps, three major and nine smaller ones were offline Thursday night, city records show. Also, all 24 major pump stations had backup generators, records show, as only three of five turbines that help power the city's oldest, most powerful pumps were available for service, a city water utility spokeswoman told CNN.
"Residents who live inside the levee system should prepare to take shelter with essential supplies including food, water, and medications," the mayor said Thursday.
Edwards authorized 1,300 National Guard troops to mobilize ahead of the storm, with some headed to New Orleans to help monitor the pumps, he said.
Storm due to move through quickly
Nate would be the first hurricane to hit Louisiana since Hurricane Isaac in 2012 as a Category 1 storm.
"It will still be fairly strong when it makes landfall, but it will be a quicker moving storm than the last few we have had," CNN meteorologist Haley Brink said. "It's supposed to be in and out pretty quickly."
The storm could drop 3 to 6 inches of rain, with 12 inches possible in some areas, from the central Gulf Coast north through Tennessee, where Nate is expected to pass late Sunday, the hurricane center said.
The last hurricane to hit the Louisiana-Mississippi-Alabama region in October was Hurricane Lili in 2002. The last time three hurricanes hit the mainland in the same year was 2008, when Dolly, Gustav and Ike came through.
Gulf Coast states prepare
Though Florida remained largely out of the forecast cone, hurricane, tropical storm and storm surge watches were issued late Friday morning from the state's border with Alabama east as far as Indian Pass, the hurricane center said.
With parts of Florida still reeling from Hurricane Irma, Gov. Rick Scott declared a state of emergency for 29 counties and encouraged residents to get prepared in case Nate's forecast track changes. Evacuations could be called, he added.
"Just think about your family: Get your three days of water, three days of food; if you're taking medicine, make sure you have your medicine," Scott said Thursday during news conference.
In Alabama, a statewide emergency declaration signed by Gov. Kay Ivey went into effect Friday morning. The move "frees up personnel and resources in case there is a need to respond to any storm related activity."
Mayor Sandy Stimpson of Mobile, Alabama, warned residents Friday about storm surge.
"We encourage citizens in low-lying areas to pay special attention to newscasts," he said at a news conference. "There is a projected 4- to 7-(foot) storm surge. It will happen to coincide with high tide, which will give you additional water levels."
Mobile officials were checking storm drains for debris, taking measures to avert power outages and deploying critical equipment. Shelters were prepared to open, if necessary, Stimpson said.
"Don't wait 'til Saturday after dark to decide what you have to do in case things with the storm change," he said.
Deadly storm slams Central America
Of the 21 dead, 11 died in Nicaragua, 8 in Costa Rica and 2 in Honduras, officials said. Several people also were reported missing as the storm hit Central America.
Hundreds were rescued from floodwaters, and many had lost power and running water in Nicaragua, Honduras and Costa Rica, officials said.
The main threat for Central America was heavy rainfall, which triggered life-threatening flash flooding and mudslides.
Costa Rica President Luis Guillermo Solis declared a national state of emergency to assist those affected by the storm.
Rain will continue to fall through Friday night in parts of Nicaragua, Honduras, Costa Rica, Panama and Belize, forecasters said.