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More than 13 million Gulf Coast residents were under threat as Hurricane Nate powered toward the mainland early Saturday, bringing with it rain and storm surges to parts of Louisiana, Mississippi, Alabama and Florida.

The hurricane, with maximum sustained winds of 90 mph, is now expected to make landfall on Saturday night between New Orleans and Mobile, Alabama, as a Category 2 storm, the National Hurricane Center said Saturday morning. It was about 180 miles south-southeast of the mouth of the Mississippi River, and was moving north-northwest at 26 mph, the hurricane center said.

"Nate is at our doorstep, or will be soon," New Orleans Mayor Mitch Landrieu said at a press conference Friday. A hurricane warning has been issued for the city, which is under a state of emergency.

New Orleans could see between 3 to 6 inches of rain in all, Landrieu said, but he said wind and storm surge posed the greatest risk.

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In August, a powerful storm flooded neighborhoods throughout the city and officials acknowledged that several pumps and turbines that power the drainage system were out of service.

Since then, Landrieu said, crews have has worked hard to repair the pumps and ensure that the system can withstand the rains, but he warned residents to expect some flooding.

"While we are in a stronger place than we were in August regarding pumps and power, if this weather system strengthens and starts to produce large amounts of rainfall in short periods of time with bursts, we could see some localized flooding," he said.

Hurricane warnings were also in place for Lake Pontchartrain and a stretch of coast from Grand Isle, Louisiana to the Alabama-Florida border.

Storm surge warnings were issued for the coastline between Morgan City, Louisiana and the Okaloosa-Walton county border in Florida, as well as for the northern and western shores of Lake Pontchartrain.

Coastal and southeastern Mississippi is predicted to see storm surges of up to 9 feet above ground level, as well as power outages and hurricane force winds, said Roy Lucksinger, principle meteorologist at the Weather Channel.

There is also a risk of isolated tornadoes in the area as the hurricane makes landfall, Lucksinger said.

️All preparations along the Gulf Coast should be RUSHED TO COMPLETION this morning ahead of Hurricane #Nate! #LAwx #MSwx pic.twitter.com/s2YZk2KIoF — NWS New Orleans (@NWSNewOrleans) October 7, 2017

States of emergency were declared in Alabama and Louisiana. "Alabamians, you must prepare and remain vigilant — this is serious business," Alabama Gov. Kay Ivey said at a news conference Friday. She said the effects will begin to be felt as early as Saturday afternoon.

"By Saturday noon, you should be in your safe place," Ivey said.

Mandatory evacuations were ordered in Venetian Isles, Lake Catherine and Irish Bayou sections of New Orleans. Landrieu urged people to stay off the roads starting Saturday evening through Sunday. He said residents should stock up on supplies.

Nate is already blamed for deaths in Central America. Eleven deaths have been reported in Nicaragua, 10 deaths were reported in Costa Rica, and one person was reported killed in Honduras, officials said.