Offshore workers evacuated
Oil prices slipped on Friday after a week of volatile trading due to Gustav's threat to the 4,000 Gulf platforms that produce a quarter of US oil and 15 percent of its natural gas.
Energy companies evacuated offshore workers and shut production in preparation for the most serious Gulf storm since the devastating 2005 Atlantic hurricane season.
Katrina was a monstrous Category 5 hurricane in the Gulf of Mexico before coming ashore near New Orleans as a Category 3 on August 29, 2005, breaching protective levees and flooding the city famed as the birthplace of jazz.
The devastation exposed deep poverty, racial tensions and federal incompetence as thousands of people were left stranded without aid. About 1,500 people were killed on the US Gulf Coast and $80 billion in damages made Katrina the costliest US natural disaster.
Katrina and Hurricane Rita, which followed it, also wrecked more than 100 oil rigs.
In New Orleans on Friday, officials paused their Gustav preparations to mark the Katrina anniversary with a symbolic burial for more than 80 victims still unidentified three years later.
Louisiana authorities warned residents to prepare to evacuate and laid on transportation for those who do not have cars. Federal officials say the levees are stronger but gaps still exist that make vulnerable some of the neighborhoods hardest hit by Katrina's floods.
In the British territory of the Cayman Islands, which has not completely recovered from a near-direct hit by Hurricane Ivan in 2004, residents scurried to make last-minute purchases but only a few gas stations remained open as Gustav's rains began on Friday afternoon.
The streets of the capital, George Town, were mostly deserted, a stark contrast to the traditional weekday bustle of the financial services industry hub.
Energy traders also watched Tropical Storm Hanna, 240 miles
north of Puerto Rico. The storm was moving west-northwest with maximum sustained winds at 50 mph (85 kph) and it could be near hurricane strength by Sunday.