CORRECTED - WRAPUP 5-Hurricane Gustav blows over Caymans, heads to Gulf

(Corrects day of week in final paragraph to Sunday from Saturday)

* U.S. forecasters see rapid intensification

* Energy companies evacuate offshore workers

* New Orleans marks third anniversary of Katrina

By Alan Markoff

GEORGE TOWN, Aug 29 (Reuters) - A strengthening Hurricane Gustav swept over the Cayman Islands on Friday as it headed toward Cuba and the Gulf of Mexico on the third anniversary of Hurricane Katrina's deadly strike on New Orleans.

The storm, which killed up to 77 people in the Caribbean, was plowing toward superheated waters south of Cuba where it could absorb enough energy to strengthen into a major hurricane before ripping through the heavy concentration of U.S. oil and natural gas platforms off Louisiana.

While long-range storm forecasts are prone to errors, the U.S. National Hurricane Center said late Friday that Gustav could be a "major" Category 4 storm on the five-stage Saffir-Simpson scale of hurricane intensity within 48 hours.

The storm's most likely track has it going ashore west of New Orleans on Tuesday morning.

U.S. emergency officials 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.

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 CLc1OILOILLCOc1CLV8.

Energy companies evacuated offshore workers and shut production in preparation for the most serious Gulf storm since the devastating 2005 Atlantic hurricane season.

Gustav strengthened back into a Category 1 hurricane as it neared the wealthy Cayman Islands on Friday and it could grow into at least a Category 3 storm before reaching western Cuba on Saturday.

At 11 p.m. EDT (0300 Saturday GMT), Gustav was 55 miles (85 km) east of Grand Cayman Island and moving northwest at 10 miles per hour (17 kph). Top sustained winds were near 80 mph (130 kph).

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.  Continued...