Hurricane Dean strengthened and threatened to become a dangerously powerful storm as it plowed toward the Caribbean and aimed for Mexico's Yucatan Peninsula or the Gulf of Mexico beyond, forecasters said on Thursday.

More immediately in the path of the 2007 Atlantic storm season's first hurricane were the Lesser Antilles, in particular the islands of Dominica and St. Lucia and the French territories of Martinique and Guadeloupe, the U.S. National Hurricane Center said.

The hurricane's top sustained winds had reached 100 miles per hour (160 km per hour) by 8 p.m. EDT, making it a Category 2 storm on the five-step Saffir-Simpson scale of hurricane intensity, the Miami-based hurricane center said.

Computer models showed the hurricane could become an extremely dangerous Category 4 storm as it passed south of Jamaica early next week.

Category 3 to 5 hurricanes, such as Katrina, Rita and Wilma in the devastating 2005 Atlantic storm season, are potentially the most destructive storms but a Category 2 hurricane can still damage buildings and create a 6- to 8-foot (1.8 meter to 2.4 meter) storm surge.

"Preparations to protect life and property should be rushed to completion," the hurricane center said in an echo of warnings that rang out repeatedly in 2004 and 2005, when a series of hurricanes struck the United States, the Caribbean and Central America.

Energy markets in particular have been on edge since 2004 and 2005, when hurricanes Ivan, Katrina and Rita toppled oil rigs and flooded refineries on the U.S. Gulf Coast. The Gulf of Mexico accounts for roughly a third of domestic U.S. oil production and more than 15 percent of its natural gas.

In addition, almost half of U.S. refining capacity is located in Gulf Coast states and can be vulnerable to flooding or wind damage from storms.

If Dean crosses the Yucatan and enters the southern Gulf of Mexico, it could disrupt operations in the Cantarell Complex of Mexican oil fields, which is one of the world's most productive and supplies two-thirds of Mexico's crude oil output.


By 8 p.m. EDT, Dean was about 205 miles east of Martinique and racing westward at 23 mph (37 kph), a pace that could bring it over the Lesser Antilles islands early on Friday.

The French government issued a hurricane warning for Martinique and Guadeloupe. Hurricane warnings were also in effect for Dominica and St. Lucia, alerting residents to expect hurricane conditions within 24 hours.

In Dominica, acting Prime Minister Vince Henderson canceled leave for police, prison and fire officers and urged employers to send other workers home early to prepare.

"Let me wish all my fellow Dominicans and all our visitors a safe night and pray for God's blessings that we will see tomorrow all in one healthy and good condition," he said.

Tropical storm warnings were in effect for Anguilla, Grenada, St. Vincent and the Grenadines, Barbados, Saba, St. Eustatius, Montserrat, Antigua and Barbuda, St. Kitts and Nevis and St. Maarten.

A tropical storm watch, meaning tropical storm conditions could be expected within 36 hours, was issued for the U.S. Virgin Islands and Puerto Rico.

Meanwhile, another weather system, Tropical Storm Erin, weakened into a depression as it washed ashore in Texas northeast of Corpus Christi, spooking oil markets and killing four people. One died when heavy rains flooded Houston and caused a grocery store roof to collapse, while three were killed in a car crash blamed on wet roads.

Forecasters have predicted the six-month hurricane season that officially began June 1 would be more active than average with up to 16 named storms. An average year historically has 10 to 11 storms, of which six strengthen into hurricanes.

(Additional reporting by Tom Brown in Miami and Bruce Nichols in Houston)