Jamaicans rushed to stock up on emergency supplies and officials urged coastal areas evacuated Friday as a slightly weakened Hurricane Emily (search) churned toward the Caribbean island after ravaging Grenada.

Packing winds of 115 mph, the second major hurricane of the Atlantic season came unusually early and made its presence felt hundreds of miles away, unleashing heavy surf, gusty winds and torrential rains on islands both sides of the Caribbean sea.

The category 3 storm (search) was just over 300 miles southeast of Jamaica's capital and was moving westward at nearly 18 mph, with a turn toward the northwest expected to take it very close to Jamaica on Saturday, according to the National Hurricane Center (search) in Miami.

If Emily continues on the same path, the storm will make landfall sometime Wednesday between Tuxpan, Mexico, and Galveston, Texas, about a 600-mile span, hurricane center spokesman Frank Lepore said, cautioning that "a lot could change between now and then."

Jamaica posted a hurricane warning. Prime Minister P.J. Patterson ordered government offices to close early Friday and instructed disaster authorities to draw up plans to evacuate thousands of residents in flood-prone coastal areas.

Jamaicans formed long lines at grocery stores to stock up on water, canned food and batteries, only a week after doing the same for Hurricane Dennis, which washed away several homes, damaged crops and flooded roads.

Many islanders refused to seek shelter during Dennis, fearful of leaving their belongings unguarded.

"I'm hoping that those who are in these areas will heed the call to evacuate before it's too late," Transport and Works Minister Robert Pickersgill said on RJR radio.

Grenada — still recovering from the devastation of last year's Hurricane Ivan — declared a national disaster Friday, a day after Emily destroyed at least 16 homes, blasted out windows, sheared off roofs and flooded two hospitals and scores of other buildings.

Landslides and fallen trees blocked roads, streets were flooded and crops were destroyed. At least one person was killed in Grenada, a man whose home was buried under a landslide.

Emily's winds decreased to about 115 mph Friday evening after reaching a high of 135 mph earlier in the day, making it briefly what meteorologist Stacy Stewart called a "very rare Category 4 hurricane in the Caribbean Sea in the month of July."

The State Department issued a travel warning for Jamaica and the Cayman Islands, which were expected to get hit hard on Sunday, and authorized the departure of non-emergency staff at the U.S. Embassy.

Heavy rains drenched the southeast Dominican Republic and officials warned boatmen there to stay in port, saying that coastline could expect strong electrical storms, whipping winds and waves higher than 10 feet.

The eye of the storm was projected to come within 40 miles of Grand Cayman Island on Sunday, the Cayman Islands government warned residents. Emily's next direct hit, according to the hurricane center's projections, was expected to be Mexico's Yucatan Peninsula late Sunday or early Monday.

In Grand Cayman, Texan Carolyn Parker, said she was more apprehensive than she's ever been in 20 years as a resident of the Cayman Islands. "Ivan was pretty nasty, and I'm scared to go through that again." said the retired police officer.

Emily trails Hurricane Dennis, which destroyed crops, killed at least 25 people in Haiti and 16 in Cuba and stranded thousands of Jamaicans when it collapsed a bridge last week.

Last year, three catastrophic hurricanes — Frances, Ivan and Jeanne — tore through the Caribbean with a collective ferocity not seen in years, causing hundreds of deaths and billions of dollars in damage.

Emily struck hard in Grenada, especially in the north and in the outlying islands of Carriacou and Petit Martinique, where residents were without electricity and water, authorities said.

The damage came as the island nation still was recovering from Ivan, which last year killed 39 people, left a wasteland of ruined buildings and damaged 90 percent of the historic Georgian buildings in the capital, St. George's.

In Trinidad, widespread flooding triggered landslides that cut off the only access road to two east coast communities, marooning hundreds of residents, Mayor Eustace Nancis said.

The hurricane brought heavy rains and flooding to Venezuela, and forced 64 families out of homes when rivers overflowed their banks, a government official said Friday. As the storm moved away, the government lifted restrictions on maritime travel that had grounded oil tankers in the world's fifth largest oil exporter.

The Organization of American States called an emergency meeting of its disaster committee Friday, expressing concern at the prospect of a "severe economic setback" to countries hit by hurricanes, especially Grenada.

Forecasters have predicted up to 15 Atlantic tropical storms this year, including three to five major hurricanes. The hurricane season began June 1 and runs through Nov. 30.