What was to have been a weekend of remembrance about Hurricane Katrina's destruction became a weekend of worry as Tropical Storm Ernesto gathered strength in the Caribbean.
The US National Hurricane Center said Ernesto could grow into a Category 3 hurricane by Thursday, menacing a broad swath of the Gulf Coast. Katrina was a Category 3 storm when it ravaged New Orleans a year ago.
The weary residents of New Orleans kept an eye on the forecast.
Bari Landry, who lives in a neighborhood that was heavily flooded by Katrina, said she reserved a hotel room in Houston for Thursday through Saturday.
"There may be panic, but we know the drill," she said.
Louisiana Governor Kathleen Blanco said state officials were keeping an eye on Ernesto.
Commander of the US Army Corps of Engineers Lieutenant General Carl Strock said the Corps was carefully tracking the storm's movement.
It was too early to tell whether Ernesto would test the city's levee system, which Strock conceded may not yet be strong enough to withstand a large storm surge.
Strock said he was confident the Corps had done all it could to repair and reinforce 350km of levee walls, but said many variables would determine whether the levees could withstand a major hurricane.
Much would depend on where the hurricane hit land, wind speed, rainfall and other factors, he said.
The biggest concern would be water levels so high that they could cascade over the levee walls, weakening them to the point of breaching, he said.
"It's critical we make the right call for the right reason," Blanco said, citing the need to prevent premature evacuations.
Mandatory evacuations in the parishes below New Orleans would kick in when the storm was 50 hours from the coast, New Orleans Homeland Security chief Terry Ebbert said.
New Orleans would begin mandatory evacuation at the 40-hour mark, he said.
The city has already contracted for buses and trains to evacuate people who do not have the means to leave, he said.
Ernesto attracted attention during a weekend of events marking the anniversary of Katrina. Driving rain soaked people gathered outside the Superdome for one observance, but the storms were not related to Ernesto.
Strock appeared with Blanco and Donald Powell, the chairman of the office charged with rebuilding the Gulf Coast, at a news conference to show new protections that have been installed since Katrina, including flood gates that can be dropped into three large canals to reduce the effect of water surging out of Lake Ponchartrain.