VIDEO: Gustav rolls through Haiti

KINGSTON (Reuters) - Jamaicans deserted the streets and government offices closed as a strengthening Tropical Storm Gustav took aim at the island on Thursday on a path toward the Gulf of Mexico oil fields as a powerful hurricane.

As Gustav churned through the Caribbean, Tropical Storm Hanna formed in the Atlantic Ocean with 40 mph winds and a track that could take it toward the Bahamas and Florida next week, the U.S. National Hurricane Center said.

Energy companies prepared for a direct hit in the heart of the U.S. Gulf oilpatch and crude futures rose more than $2 at one point to $120.50 a barrel before falling back to as low as $114.08.

Energy traders were anxiously watching Gustav's track, which could take it deep into a concentration of oil and natural gas platforms off Louisiana and Texas.

The area, which provides the United States with a quarter of its crude oil and 15 percent of its natural gas, was battered in 2005 by two major hurricanes, Katrina and Rita.

The seventh storm of what experts expect to be an unusually busy Atlantic hurricane season was 45 miles east of Kingston, Jamaica, by 11 a.m. EDT and its top sustained winds had risen again to 70 mph, just short of the 74 mph hurricane threshold.

New Orleans, the southern U.S. city devastated by Katrina three years ago, remained near the middle of the Miami-based hurricane center's range of possible landfall locations on the U.S. Gulf Coast.

Louisiana Gov. Bobby Jindal put New Orleans residents on alert for possible evacuations from Friday, the third anniversary of Katrina's strike.

In Jamaica, post offices, schools and tax offices shut their doors and authorities ordered nonessential workers to stay home as Gustav neared after taking an unexpected jog south toward the capital and the southern coast.

"It was not raining heavily, so I decided to go out to work, but my employer said that I should go back and prepare for Gustav just in case it develops into a hurricane," said Trevor Bryan, a Kingston welder.

Emergency officials on the lush, mountainous island urged residents to avoid gullies and flooded waterways, evacuate low-lying areas and wrap important documents in plastic to protect them from water.

REGAINING STRENGTH

Gustav barged ashore as a hurricane in Haiti on Tuesday and its torrential rains killed at least 23 people there and in the neighboring Dominican Republic.

The storm slowed over Haiti's mountains but began to strengthen quickly on Thursday.

"It is expected that Gustav will be a powerful hurricane as it moves into the southern Gulf of Mexico on Sunday," the hurricane center said.

Gustav is the first serious Atlantic storm since the devastating 2005 hurricane season to threaten New Orleans and the Gulf oil installations.

Katrina and Rita slashed Gulf oil production that year when they swept through as Category 5 storms on the five-step Saffir-Simpson scale of hurricane intensity, damaging platforms and severing pipelines.

Energy companies shut down production and pulled workers from offshore rigs on Thursday. The International Energy Agency said member nations were prepared to release strategic oil stocks if Gustav deals a blow similar to Katrina and Rita.

Forecasters said Gustav could graze the southern coast of Jamaica as a hurricane, then threaten the wealthy Cayman Islands offshore financial center and western Cuba before entering the Gulf between Cuba and Mexico's Yucatan Peninsula.

Energy traders also warily watched newborn Hanna, 305 miles

northeast of the northern Leeward Islands. The storm was moving to the west-northwest at 12 mph and was expected to become a hurricane by Sunday.

Some computer models indicated Hanna would eventually turn to the west or even southwest and projected it would become an "intense" or "major" Category 3 or higher storm that could take aim at Florida or the Caribbean islands.

Katrina came ashore near New Orleans on August 29, 2005, as a Category 3 hurricane and flooded the city after swamping its protective levees. The hurricane killed 1,500 people along the U.S. Gulf Coast and caused at least $80 billion in damage.

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