New Orleans area residents should prepare for likely flooding and perhaps up to a week without power when Tropical Storm Nate makes landfall this weekend, likely as a Category 1 hurricane, city officials said Thursday.

With the Sewerage & Water Board’s drainage system improved but still at diminished capacity in the wake of the Aug. 5 flooding, and facing the possibility of a direct hit by Nate, Mayor Mitch Landrieu declared a state of emergency for the city.

City agencies are readying for the storm but also telling residents to be prepared for flooding in some areas.

“When you get 5 to 10 inches of rain in two or three hours, you’re going to expect to see some flooding,” regardless of how many pumps are operating, Landrieu said.

“An expectation of being dry 100 percent of the time when you live in New Orleans is not a reasonable expectation,” he added.

The city's pumping stations will be fully manned, though many are still below their full capacity, and the police, fire and EMS departments will have additional staffing through the weekend, officials said.

The city is preparing locations where people can go to fill sandbags, and barricades have been placed near underpasses to block those streets if they flood.

New Orleans has been on edge throughout the summer, first due to flooding from heavy rainfalls in July and August that revealed serious problems with the S&WB’s drainage infrastructure and then from the possibility of falling within the paths of Hurricanes Harvey and Irma. Those storms instead caused major flooding and damage in Texas and Florida.

This time, it appears New Orleans is squarely in Nate’s path, though it is expected to be less powerful and destructive than the earlier storms.

Forecasters predict Nate will strike the area as a relatively weak hurricane late Saturday or early Sunday, after intensifying over the Gulf.

Those predictions also suggest the storm will be moving quickly when it arrives, a bit of good news since it means the city will not be stuck under heavy rains for as long.

Officials are mainly concerned about high winds that could knock out power lines and do other damage. Landrieu urged residents to be prepared with supplies and batteries to get by for several days without power.

Entergy spokeswoman Melonie Stewart said that based on prior experience, the utility is expecting a strong tropical storm or Category 1 hurricane could leave some areas without power for up to a week.

The local utility’s crews that were helping with the recovery elsewhere following Harvey and Irma have returned, and Stewart said there are no concerns about getting more workers in to help reconnect power after the storm if needed.

But questions remain about how well the drainage system will handle the rain that is expected, especially in light of problems that continued to plague the S&WB as recently as Monday’s storm.

Current forecasts call for between 3 inches and 6 inches of rain to fall over the course of the storm, with those totals possibly doubled in some areas. Even at the low end, that would be far more than the most optimistic projections about how well the drainage system can keep up.

Up to 9 inches fell in some areas during the Aug. 5 flood.

As of Thursday, 108 of the 120 pumps that form the heart of the city’s drainage system were working. That’s four more than were working on Aug. 5.

Eight of the ones out of commission are the large drainage pumps used during storms, while four are small “constant duty” pumps only used for light rains.

As a result, eight of the 24 pump stations across the city are at between 50 percent and 96 percent of their theoretical maximum capacity, according to information from the S&WB.

Among those is the massive Pump Station 6, which pulls water from smaller pump stations that cover much of the area extending from the Central Business District to Metairie. That station, on the 17th Street Canal, is currently at 87 percent of its maximum capacity.

Other stations with diminished capacity include those that drain Mid-City, the two stations that serve the West Bank and three stations in New Orleans East.

“We're not where we want to be with our pumping capacity, but we're better than we were,” Councilman Jason Williams said.

Repairs have also been made to the S&WB’s power system, though officials said they could not specify how many pumps could be powered because of the complexities of how power is shuffled through the system.

With three of its five turbines operational, the S&WB’s Carrollton power plant is now capable of producing or converting 39.25 megawatts of 25-cycle power, a standard used by about half the pumps in the city. Another 11 megawatts of the more standard 60-cycle power — used by the rest of the pumps — is available from 26 generators.

But that is not enough for the S&WB to run all its pumps at once, meaning officials could have to pick and choose where to direct power during a citywide storm. Logs from the Aug. 5 flood suggest that S&WB officials delayed turning on at least one pump station because power was not available.

Interim management team member Paul Rainwater cited the complicated dance the utility goes through during every storm to route power where it’s needed most and said of the pumps, “You don’t turn them on and run them full throttle all the time.”

Landrieu sounded a similar note. “We’ve run a lot of different scenarios to get power to the pumps where they’re needed,” he said.

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City officials conducted a "table-top exercise" Thursday morning to plot how they would respond to the storm, and Landrieu said he’s been in touch with both Gov. John Bel Edwards and FEMA to discuss the response.

Officials urged residents to stay off the road during a storm and warned that police will be enforcing prohibitions on speeding through flooded streets, which can push floodwaters into buildings. Residents were advised to move vehicles to higher ground such as sidewalks or neutral grounds in advance of the anticipated street flooding.

Crews have begun closing floodgates to prepare for the storm, though they reopened passageways at Bayou Dupre and Caernarvon on Thursday to let vessels inside the storm protection system before the storm. More than 140 came through during that time.

Meanwhile, suburban parishes are also preparing. St. Bernard Parish has issued a mandatory evacuation order for all areas outside the flood protection system, and officials at Grand Isle in Jefferson Parish called for a voluntary evacuation.

In New Orleans, officials urged residents to assist the city in cleaning out catch basins in their neighborhoods. City crews and contractors on 14 vacuum trucks have cleaned out more than 3,500 catch basins since August, but there are 65,000 in the city.

“I’m going to ask everyone who can do it to find one catch basin and clean it,” City Councilman James Gray said, echoing a sentiment offered by other members of the council and administration.

Others also urged preparedness.

“The people of New Orleans have been here before. We just need to act like it,” Williams said.

Follow Jeff Adelson on Twitter, @jadelson.​