Aug. 27 (Bloomberg) -- Tropical Storm Gustav drenched Haiti today and menaced Cuba, Jamaica and the Cayman Islands while setting a likely course for the U.S. Gulf Coast region devastated by Hurricane Katrina three years ago.

Gustav, which weakened from a hurricane as it passed over Haiti, is likely to regain power in the Caribbean and may intensify into a Category 3 hurricane or stronger as it enters the Gulf of Mexico by the weekend, forecasters say. Crude rose as the storm was forecast to hit the Gulf's oil-producing region.

``This storm remains likely to explode into a major hurricane over the northwestern Caribbean'' on Aug. 29, said Jim Rouiller, a senior energy meteorologist with Planalytics Inc., a forecaster based in Wayne, Pennsylvania.

Gustav killed at least 22 people in Haiti and the Dominican Republic as it passed over the island of Hispaniola, which they share, the Associated Press reported yesterday. A hurricane warning was in effect for parts of southern Cuba.

Gustav, packing sustained winds near 45 miles (75 kilometers) per hour, down from about 60 mph earlier today, was 65 miles south of Guantanamo, Cuba, just before 8 p.m. Miami time, the U.S. National Hurricane Center said in an advisory.

It was moving west-northwest at about 7 mph, a path that should take it between Jamaica and Cuba tomorrow, the advisory said. Gustav may regain hurricane strength as soon as tomorrow.

Dumping Rain

As much as 25 inches (64 centimeters) of rain may fall in parts of the Dominican Republic, Haiti, eastern Cuba, Jamaica and the Caymans, the center said.

Louisiana Governor Bobby Jindal declared a state of emergency today, WWL-TV reported. Jindal also asked the White House to issue an emergency declaration before the storm hits land, according to the news station.

New Orleans Mayor Ray Nagin said in a statement he'd leave the Democratic National Convention in Denver to head home and manage preparations for the storm.

The Federal Emergency Management Agency was on alert and said it had food, water and supplies ready to move into the area.

New Orleans is planning a commemoration on Aug. 29 of the third anniversary of Hurricane Katrina, the most economically destructive hurricane in U.S. history. Katrina cost the Gulf coast states hit by the storm as much as $125 billion, according to the National Oceanic and Atmospheric Administration.

``The upper Texas coastline to Louisiana remains most at risk,'' Rouiller said. ``The entirety of the Gulf energy production region remains under the gun.''

Oil Production

U.S. oil and gas platforms and pipelines are most concentrated in the waters south of Louisiana and east of Texas. Offshore fields in the Gulf accounted for 26 percent of total U.S. crude production and 12 percent of natural gas output in April, according to the U.S. Energy Department.

In August and September 2005, U.S. crude oil and fuel production plunged and prices rose to records when hurricanes Katrina and Rita shut refineries and platforms as they struck the Gulf coast. Katrina closed 95 percent of offshore output in the region. Almost 19 percent of U.S. refining capacity was idled because of damage and blackouts caused by the hurricanes.

Louisiana has 19 oil refineries, which together process almost 3 million barrels a day. Those closest to the coast include ConocoPhillips' Belle Chasse refinery and Petroleos de Venezuela SA's Chalmette plant, both near New Orleans, and several refineries clustered near Lake Charles, in the southwest corner of the state.

Evacuating Workers

``Several thousand'' of the almost 20,000 workers on offshore platforms in the Gulf of Mexico, about one-quarter of whom are needed to maintain production, were to be evacuated today, Ted Falgout, director of Port Fourchon in Louisiana, said in an interview. The port is a staging area for offshore workers.

Crude oil for October delivery rose 11 cents to $118.26 a barrel at 8:44 a.m. Sydney time on the New York Mercantile Exchange. Prices are up 65 percent from a year ago.

``Right now we're forecasting Category 3, and one category higher or lower is not out of the question,'' Eric Blake, a meteorologist at the hurricane center, said today in a phone interview.

Category 3 storms on the five-step Saffir-Simpson scale of intensity have sustained winds of at least 111 mph, while Category 4 hurricanes blow at a minimum of 131 mph. A weather system is designated a tropical storm when sustained winds reach 39 mph, and a hurricane at 74 mph.

To contact the reporters on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net; Ryan Flinn in San Francisco at rflinn@bloomberg.net

Last Updated: August 27, 2008 20:59 EDT