NEW ORLEANS -- The National Hurricane Center said Thursday night that warnings remained in effect for Jamaica and the Cayman Islands.

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Meteorologists said warm waters in the Gulf of Mexico are likely to strengthen the storm, which they expected to become a Category 3 hurricane and make its way toward the Gulf Coast.

A hurricane watch remained in effect for western Cuba, for the provinces of Isla De Juventud, Pinar Del Rio, La Habana, and Ciudad De La Habana.

A tropical storm warning remained in effect for the Cuban province of Granma.

A tropical storm watch remained in effect for the Cuban province of Matanzas.

At 11 p.m. EDT, the center of Tropical Storm Gustav was located near latitude 17.8 north, longitude 77.3 west or about 35 miles west-southwest of Kingston, Jamaica and about 275 miles east-southeast of Grand Cayman.

Gustav is moving toward the west near 7 mph. A turn toward the west-northwest and northwest is forecast during the next couple of days.

On this track, the center of Gustav will pass near or over western Jamaica Thursday night, move near or over the Cayman Islands Friday or Friday night, and approach western Cuba on Saturday.

Maximum sustained winds are near 70 mph, with higher gusts. Strengthening is forecast during the next 24 hours, and Gustav is expected to become a hurricane Friday or Friday night.

Tropical storm force winds extend outward up to 45 miles from the center.

Gustav is expected to produce total rainfall accumulations of 6 to 12 inches across Jamaica and the Cayman Islands, with isolated maximum amounts of up to 25 inches possible. These rains will likely produce life-threatening flash floods and mud slides.

Rainfall accumulations of 2 to 4 inches are possible over southern Cuba. Rainfall will be diminishing over Haiti Thursday night, with an additional 1 to 2 inches of rainfall possible.

The city's homeland security chief, Colonel Jerry Sneed, spoke at a press conference where he told New Orleanians to be prepared, have a bag packed, and be ready to heed evacuation warnings.

"A mandatory evacuation is not a forced evacuation but when the mayor tells you it’s a mandatory evacuation, you should heed his warning and leave," Sneed said. "You assume all responsibility. At some point, there will be a curfew and, if you are found not on your property, you will be put under arrest."

Coastal storm surge flooding of 2 to 4 feet above normal tide levels can be expected near and to the east of where the center makes landfall.