SAN JUAN, Puerto Rico - Tropical Storm Ernesto strengthened over the Caribbean Saturday as it headed toward Jamaica and the Cayman Islands, threatening to become the first hurricane of the 2006 Atlantic season, the U.S. National Hurricane Center said.
Ernesto, which formed Friday, was projected to reach hurricane strength early next week and enter the Gulf of Mexico on Tuesday or Wednesday, but it was too soon to predict whether it would hit the United States, forecasters said.
"At this early stage, the message we want to send to people is not to panic, but to watch it," said Jamie Rhome, another specialist at the hurricane center.
Ernesto was on a course that would bring it over Jamaica by Sunday afternoon, dumping heavy showers. Fishermen were warned to return to shore and Prime Minister Portia Simpson Miller met with disaster agencies to prepare.
Ernesto has the "potential to turn into a hurricane, so we must be on the alert for storm surges and damage to property," said Nadine Newsome, of the Office of Disaster Preparedness and Emergency Management. The office provided hurricane survival tips to locals living in four parishes prone to extensive damage from rains.
The Cayman Islands' National Hurricane Committee issued a tropical storm alert for the islands, meaning the storm should hit the British territory within two days. The local weather service projected that tropical storm force winds would hit some areas starting late Sunday.
At 8 a.m. EDT Saturday, Ernesto had maximum sustained winds near 50 mph with higher gusts. The fifth named storm of the Atlantic hurricane season was centered 245 miles south of Santo Domingo, Dominican Republic and 455 miles southeast of Kingston, Jamaica. The storm was moving northwest at nearly 15 mph.
People were advised to complete their weather preparations on Saturday.
Jacky Kennett, who moved to the Cayman Islands with her family from Britain a year ago, was preparing for what could be her first hurricane.
"I went and put fuel in the car, got some money out of the bank, and stopped at the grocery store yesterday to stock up," said Kennett, 47. "I don't want to overreact or anything, but I am worried."
Fears that the storm could damage offshore energy facilities in the Gulf of Mexico sent oil and natural-gas prices higher. Oil producers operating in the Gulf said they were prepared to evacuate nonessential personnel if needed.
Max Mayfield, the National Hurricane Center director, said it was too early to say whether the storm would hit the U.S. Gulf Coast, which is still recovering from last year's Hurricane Katrina.
"It's too early to pinpoint one specific location but I think message is, especially to the folks that are in temporary housing, these 115,000 families mostly in the FEMA trailers, they need to watch this carefully," Mayfield told CNN's Wolf Blitzer. "We've got some time. We don't want people to get too excited about this, but they certainly need to be watching it."