With Tropical Storm Harvey still making its slow and unpredictable crawl along the Texas coast and with major questions remaining about New Orleans’ pumping capacity, Mayor Mitch Landrieu on Monday called on the city to essentially shut down ahead of potentially heavy rains Tuesday.

Heavy rain bands from the storm, which has dumped record amounts of rainfall in Texas, are expected to start hitting the New Orleans area by Tuesday, leaving city officials warning of potential flooding on the 12th anniversary of Hurricane Katrina.

With its diminished pumping system, New Orleans is the only government in the area concerned enough about potentially heavy but not catastrophic rainfall to urge emergency measures.

A potential test of the city’s fragile drainage system during brief but heavy storms on Monday provided little comfort, as both a recently repaired pump and a piece of power equipment had to be taken offline when they broke during the rains.

Monday's rain led to street flooding in Mid-City, Lakeview and Gentilly, again raising questions about the drainage system's current capacity, which was first called into question after the Aug. 5 flood exposed serious problems with equipment and staffing.

Those problems, as well as continued uncertainty about Harvey’s path and impacts, appeared to have Landrieu and other city officials on edge Monday and expressing further doubts about the Sewerage & Water Board’s longtime assurances about the capacity of the drainage system.

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New Orleans is under the threat of flash floods, and National Weather Service forecasters have warned of possible tornadoes connected to the storm.

“How much more uneasy could you feel right now in the city of New Orleans, other than to say, 'There but for the grace of God go I in Houston'?” Landrieu said in response to a question about the chance of flooding on the anniversary of Katrina.

“It’s a very difficult day for everybody in New Orleans because those images (from Houston) bring us immediately back to (Katrina), and given all the things that have happened to us, it will make us anxious.”

Landrieu called for the closure of all city offices — including the S&WB's — on Tuesday and urged residents to stay at home that day, saying that decisions would be made later about how the city should approach the rest of the week. Schools and universities in the city also announced closures.

Officials urged residents to avoid driving if possible and to move their vehicles to higher ground if necessary to prevent flooding.

The warning came with familiar calls not to drive through flooded streets or underpasses, to leave flooded cars even if they are blocking lanes of traffic and not to block streetcar tracks when parking on neutral grounds.

New Orleans is expecting a total of 4 to 10 inches of rain through Sunday, a forecast that has changed little in recent days. But judging by Monday's downpour, it seemed that some areas might well experience much higher totals before Harvey is done making its way through the state.

The rain is likely to lessen during the latter half of the week, the National Weather Service said.

“We can stand it,” said Gavin Phillips, a forecaster with the service's New Orleans/Baton Rouge office, said of what is expected. “There could be some flooding with it, but for the most part it doesn’t look like there’s anything we can’t deal with.”

There’s still a chance some rain bands could stagnate over New Orleans, which would potentially bring double the predicted rainfall. Those bands are highly unpredictable.

However, even as Harvey drifts offshore, the chance it could gain strength over the Gulf of Mexico’s warm waters and rebound as a hurricane remained low Monday, Phillips said. That’s because much of the storm remains over land, its core is weak and it won’t stay in the Gulf for long.

Instead, it is expected to travel upward through Texas to northwest Louisiana and Arkansas and later Missouri, where it will weaken further and eventually dissipate.

“This storm has everything bad about it you could want in a storm,” Landrieu said.

Monday’s brief deluge exposed the fragility of the repairs so far to the city's drainage system.

A recently repaired pump caught fire and had to be taken offline at the critical Pump Station No. 6, which helps push water into the 17th Street Canal from areas stretching from the Central Business District to Carrollton and also serves Old Metairie and Old Jefferson. That one pump provides more than a tenth of the station’s maximum capacity.

Overall, about 94 percent of the capacity provided by the city’s 100 main drainage pumps is now online, as is about 69 percent of the capacity provided by 20 small “constant duty” pumps typically used only on relatively dry days.

More problems cropped up when a frequency changer at the S&WB power plant, which is used to convert electricity from Entergy to the older standard used by about half of the city’s pumps, had to be taken offline because of moisture issues. It is not clear when it will be brought back online.

The power situation as a whole remains one of the most precarious elements of the system. Only two of the five turbines that provide power to the pumps are working, though the system typically can also draw power from Entergy. A third turbine was expected to be repaired by midday Tuesday.

Officials could not say how much of the system could be powered by the amount of electricity now available. Paul Rainwater, a member of the interim management team at the S&WB, said determining that capacity is “not an exact science” due to the two different power standards in use and the ability to shuffle electricity through the system to the pumps most in need.

Landrieu and other officials have previously backed off the familiar claim, made for many years, that the drainage system can handle an inch of rainwater in the first hour and a half-inch every hour after that. 

“I haven’t seen any evidence of that. I’m questioning everything now,” Landrieu said Monday. “I don’t know whether it means we’re better or worse. I don’t know.” 

New Orleans experienced its first wave of heavy rainfall from Tropical Storm Harvey on Monday, with some areas getting more than 3 inches of rain in little more than an hour.

Areas in Lakeview saw the worst of the sudden downpour Monday afternoon, with up to 3.5 inches of rain falling between 1 p.m. and 2 p.m., according to the online forecasting service Weather Underground. Gentilly saw 2 inches.

Elmwood and River Ridge in Jefferson Parish got between 2 inches and 2.5 inches of rain in less than two hours.

By 3 p.m. Monday, more than 50 locations in parts of Mid-City, Lakeview, Gentilly and New Orleans East had experienced street flooding, according to Streetwise, an online tool residents can use to track flooding and traffic incidents in real time in their areas. The updates are based on calls for service made to 911.

Local education officials said that all New Orleans public schools would be closed Tuesday. Catholic schools in Orleans Parish will also close, the Archdiocese of New Orleans said.

The University of New Orleans canceled classes on Monday afternoon because of "heavy" street flooding around the school's lakefront campus. UNO and most other universities and colleges in the city will also be closed on Tuesday.

Follow Jeff Adelson on Twitter, @jadelson.​