MIAMI—Hurricane Gustav strengthened into a major Category 3 storm on Saturday as it moved over warm Caribbean waters toward western Cuba, the U.S. National Hurricane Center said.
Just before 6 a.m. (1000 GMT), the storm had maximum sustained winds near 115 mph (185 kph), making it a Category 3 storm on the five-stage Saffir-Simpson scale of hurricane intensity.
Any storm packing winds of at least 111 mph (178 kph) is ranked "major" by the Miami-based hurricane center.
The storm, which killed up to 77 people in the Caribbean, is still on track to strike the heavy concentration of U.S. oil and natural gas platforms off Louisiana. The most likely track has it going ashore west of New Orleans on Tuesday.
While long-range storm forecasts are prone to errors, the U.S. National Hurricane Center said late Friday that Gustav could become a Category 4 storm within 48 hours.
In the hurricane center's latest advisory, it said six to 12 inches (15 to 30 cm) of rain could fall across the Cayman Islands and central and western Cuba, where flash flooding and mudslides were possible.
One to three inches (2.5 to 8 cm) of rain could fall over the Florida Keys and the southernmost parts of Florida by Sunday morning, it said.
U.S. emergency officials, mindful of the devastation caused by Hurricane Katrina three years ago, warned that Gustav was expected to be accompanied by a 15- to 30-foot (5-to-9 metre) storm surge along the Gulf Coast, and said four states in its potential path were expected to begin large-scale evacuations on Saturday.
"This storm has the potential for being a very dangerous storm," said Bill Irwin, a program director with the U.S. Army Corps of Engineers.
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 U.S. 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 Aug. 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 U.S. Gulf Coast and $80 billion in damages made Katrina the costliest U.S. 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 (390 km) 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.
