NEW ORLEANS — Laurent Paige, 66, waved to his neighbor on Friday from his front-porch swing in the Broadmoor neighborhood of this city.
“I’m ready — I got my life jacket,” he hollered, pantomiming some swim strokes.
New Orleans residents like Mr. Paige were keeping an eye on Tropical Storm Nate, the latest system of this busy Atlantic hurricane season. It strengthened into a hurricane on Friday night and could hit the Gulf Coast late Saturday or early Sunday.
While forecasters believe that the brunt of the storm will slide east of New Orleans, Mr. Paige was taking no chances and stockpiled bottled water, batteries and ready-to-eat food.
And yet: “I really don’t think that this storm, Nate, is anything to be scared of,” he said with the confidence of someone who has endured more than six decades of hurricane seasons. What did worry him, though, was the water that will fall and accumulate — and might not move for a while.
In the past, New Orleans residents feared that the levees that protected the city would give way, and much of the city was flooded when the levees did just that in 2005, after Hurricane Katrina. Now concerns have shifted to the city’s antiquated and hobbled interior-drainage system, which has been plagued by breakdowns.
With the city relying on a network of century-old pumps, the malfunctions have left it vulnerable to flooding from even ordinary rainstorms. Now the system may have to reckon with a hurricane.
The authorities in Central America have blamed Nate for at least 22 deaths, and the storm moved quickly toward the United States on Friday. It was expected to be well into the Gulf of Mexico by Saturday morning, taunting and frustrating forecasters. Even as the outlook became more refined, the storm’s strength seemed to be its central mystery.
Nate’s sustained winds increased late Friday to hurricane force — 74 miles an hour or faster — and a growing number of forecasting models suggested that the system would ultimately arrive along the coast as a Category 1 hurricane. The storm was just above the minimum for a hurricane on Friday night, but with Nate poised to spend Saturday traversing hundreds of miles of warm gulf waters that have a long history of strengthening storms, forecasters cautioned that Nate could become more powerful.
“Conditions appear favorable for continued strengthening up to landfall on the northern Gulf Coast, and Nate is expected to make landfall there as a hurricane,” the National Hurricane Center in Miami said in one of its updates on Friday night. The forecasters warned of “rapid intensification.”
While the authorities remained uncertain of just how strong Nate would become, they were becoming more confident about where it would go, and they feared it would bring a storm surge that could be life-threatening.
Officials said the eyewall of the storm was likely to pass over, or very near, southeast Louisiana before moving toward the Alabama and Mississippi coasts. A hurricane warning was in effect for parts of Alabama, Louisiana and Mississippi, and the authorities posted a hurricane watch for a stretch of the Florida Panhandle.
No hurricane has made landfall in Louisiana since 2012, when Hurricane Isaac moved ashore near the mouth of the Mississippi River. Mississippi has gone even longer without a hurricane landfall: Its last was Katrina, in 2005.
“I would ask the public not to look at the center of circulation, not to guess where the storm is,” said Lee Smithson, the executive director of the Mississippi Emergency Management Agency. “This storm will impact the entire Mississippi Gulf Coast. Our plans are no good if the public does not heed the warnings that we’re putting out.”
A weakened storm, most likely a tropical depression, could sweep over Virginia on Monday. But before Nate reaches that part of the country, the Hurricane Center said, the storm was likely to produce notable rainfall totals from the Gulf Coast through southern Appalachia.
Some local governments in Louisiana ordered evacuations, and New Orleans imposed a curfew that is to begin on Saturday. New Orleans officials also said people would be allowed to park their cars on raised street medians, and officials warned that high winds could leave parts of New Orleans without power for up to a week.
“There will be standing water in the streets,” warned Mayor Mitch Landrieu, who urged residents not to drive and has spent his waning months in office coping with the city’s drainage troubles.
The extent of problems were brought to light this summer, after a New Orleans City Council hearing that looked into the extensive flooding that followed a severe thunderstorm on Aug. 5. After the storm dumped about 10 inches of rain, hundreds of cars and properties flooded.
The problems infuriated Mr. Landrieu, who has cultivated a reputation as a pragmatic manager. After the hearing, which revealed unmanned and broken pumps and stalled drain-cleaning plans, Mr. Landrieu fired some officials, telling them that their “obfuscation” was “insulting to the public.”
Now Mr. Landrieu’s makeshift, rapidly developed response will be tested, as will the team he appointed to deal with the drainage problems. The system has, so far, shown signs of improvement. Still, after a rainstorm went over New Orleans on Monday, several cars were mired in knee-deep water.
With the latest storm approaching, a handful of pumps are still inoperable, and city officials said they had made arrangements to monitor and staff all pumping stations. Even with additional personnel, supported by National Guard troops who were deployed to New Orleans ahead of the storm, the city will still face the challenge of running the system without a fully functioning network of steam turbines that provide power.
They are likely to have little choice but to shut off some pumps in order to turn on others where the flooding could be more severe.
During the rainstorm on Monday, Mr. Paige said the water rose above the curb. That made him uneasy, especially because he had already used a tire iron to open his catch basin’s heavy lid and clean out debris.
He was hoping, even with weeks left to go in the hurricane season, that the crisis would be nearing its end.
“It’s getting too late for more hurricanes,” he said. “It’s October. Nate is going to be it. It’ll be the last one.”
So this city hoped.
Katy Reckdahl reported from New Orleans, and Alan Blinder from Atlanta. Matt Stevens contributed reporting from New York.