The National Hurricane Center in Miami projected that Nate would brush by the southeast tip of Louisiana, near the mouth of the Mississippi River, around 7 p.m. Saturday. A late Saturday landfall projected for the Mississippi Gulf Coast posed a multitude of threats, including heavy rain, high tides and strong winds.
States of emergency were declared in Louisiana, Mississippi and Alabama; officials announced evacuation orders in low-lying areas and the opening of shelters for anyone who needs them.
As often happens when storms approach, waterside sections of New Orleans, outside the city's levee system, were under an evacuation order. About 2,000 people were affected. But not everyone was complying.
Gabriel Black of New Orleans' Venetian Isles community sent his wife, a friend, and three dogs to a hotel in the city. Black stayed behind because an 81-year-old neighbor refused to leave.
"I know it sounds insane, but he has bad legs and he doesn't have anybody who can get to him," Black said.
Others nearby were staying as well. Nancy and Cleve Bell said their house is built so high off the ground that it stayed dry in the floods after Hurricane Katrina. Nancy Bell said they have a generator and plenty of supplies, and will be safe.
Anticipation of Nate's high winds, rain and storm surge forced several low-lying areas to evacuate, including the barrier island town of Grand Isle, and the coastal town of Lafitte.
The vast majority of New Orleans residents were not under such an order. But a 7 p.m. curfew was declared for the city, whose fragile pumping and drainage system could face a major test once Nate strikes. System weaknesses - including the failure of some pumps and power-generating turbines - were exposed after an Aug. 5 deluge flooded homes and businesses in some sections of the city.
New Orleans Mayor Mitch Landrieu said 109 of its 120 pumps are functioning, which is 92 percent capacity. Some 26 backup generators were in place. Efforts to clean thousands of street catch basins have been stepped up, with vacuum trucks dispatched to various areas to suck out thick mud and debris.
Landrieu also said flood-prone underpasses would be blocked Saturday to keep motorists from driving into standing water.
"Right now this storm should not bring us anything that we're not prepared to handle," Landrieu said Saturday.
Forecaster said Nate could dump 3 to 6 inches (7 to 15 centimeters) of rain on the region — with isolated totals of up to 10 inches (25 centimeters).
Storm surge was as big a worry as rain. As is often done during the approach of storms, the city ordered evacuation of some low-lying communities near the water and its levee system — an estimated 1,000 homes. And communities along the Gulf and near Lake Pontchartrain were looking at the possibility of storm surge flooding.
In Mississippi, the state highway department said crews were lowering high masts that hold street lights along the coast to keep the lights from becoming projectiles in high winds.
The Bankhead Tunnel, which passes under Alabama's Mobile River, was closed, with large doors and sandbags covering the entrances.
On Alabama's Dauphin Island — a barrier island south of Mobile, Alabama — owners hauled boats out of the water ahead of the storm's approach. The major concern was the storm surge was projected to coincide with high tide. Shelters were being open for coastal residents.
Louisiana Gov. John Bel Edwards said he spoke with President Trump on Saturday morning. "He assured me that LA would have all the assistance we need as we prepare for #Nate," the governor posted on Twitter.
Nate was located at 10 a.m. CDT Saturday about 180 miles (285 kilometers) south-southeast of the mouth of the Mississippi River. It was still a Category 1 storm but was expected to gain strength before making landfall.
Nate has already killed at least 21 people in Central America.
A hurricane warning is in effect from Grand Isle, Louisiana, to the Alabama-Florida border and also for metropolitan New Orleans and nearby Lake Pontchartrain. Tropical storm warnings extended west of Grand Isle to Morgan City, Louisiana, and around Lake Maurepas and east of the Alabama-Florida border to the Okaloosa-Walton County line in the Florida Panhandle.
In neighboring Mississippi, Gov. Phil Bryant declared a state of emergency in six southernmost counties. State officials warned storm surge was the biggest danger in that state's low-lying coastal areas, as well as high winds that could damage mobile homes. The Mississippi Emergency Management Agency announced the opening of shelters on the coast Saturday.