PORT-AU-PRINCE - Hurricane Ike strengthened rapidly into an fiercely dangerous Category 4 hurricane in the open Atlantic on Wednesday and Tropical Storm Hanna intensified to a lesser degree as it swirled over the Bahamas toward the southeast U.S. Coast.

Ike posed no immediate threat to land but strengthened explosively, growing in the space of a few hours from a tropical storm to an intense Category 4 hurricane on the five-step Saffir-Simpson intensity scale.

Ike had top sustained winds near 145 mph (230 kph) as it swept across the open waters of the west-central Atlantic 550 miles (885 km) northeast of the Leeward Islands, the U.S. National Hurricane Center said. It was moving west-northwest near 17 mph (28 kph).

It was forecast to head for the southern Bahamas early next week but it was too early to tell whether it would threaten land, the forecasters said.

It was also too soon to say whether Ike would threaten U.S. oil and natural gas producers in the Gulf of Mexico.

The hurricane center's Web site, with updates and graphics.

Hanna's torrential rains had already submerged parts of Haiti, stranding residents on rooftops and prompting President Rene Preval to warn of an "extraordinary catastrophe" to rival a storm that killed more than 3,000 people in the flood-prone Caribbean country four years ago.

Hanna was forecast to move over the central and northern Bahamas on Thursday, strengthening back into a hurricane with winds of at least 74 mph (119 kph) before hitting the U.S. coast near the North Carolina-Virginia border on Saturday.

The government of the Bahamas had ended a hurricane warning for the northwestern part of the islands, meaning a tropical storm warning was now in effect for all of the Bahamas and for the Turks and Caicos Islands, the hurricane center said.


Hanna has been a "tenacious tropical cyclone" that is forecast to regain hurricane force in a day or two but possibly sooner, it said. "A hurricane watch may be required for a portion of the southeastern United States coast early Thursday," the center said.

Tropical Storm Josephine also marched across the Atlantic on a westward course behind Ike but it had begun to weaken.

The burst of storm activity follows Hurricane Gustav, which slammed into Louisiana near New Orleans on Monday after a course that also took it through Haiti, where it killed more than 75 people.

The U.S. government has forecast 14 to 18 tropical storms will form during the six-month season that began on June 1, more than the historical average of 10. Josephine was already the 10th of the year, forming before the statistical peak of the season on September 10.

The record-busting 2005 season, which included deadly Hurricane Katrina, had 28 storms.

In Haiti, officials were still counting the scores of people killed by Gustav when Hanna struck the impoverished nation on Monday night.

Authorities said Hanna caused flooding and mudslides that killed at least 61 people across Haiti, including 22 in the low-lying port of Gonaives. The death toll was expected to rise as floodwaters receded and rescuers reached remote areas.

"We are in a really catastrophic situation," said Preval, who planned to hold emergency talks with representatives of international donor countries to appeal for aid.

"It is believed that compared to Jeanne, Hanna could cause even more damage," he said, referring to a storm that sent floodwaters and mud cascading into Gonaives and other parts of Haiti's north and northwest in September 2004, killing more than 3,000 people.

Gonaives residents were still stranded on their rooftops two days after the floodwaters rose and the government did not know the fate of those who had been in hospitals and prisons.

"There are a lot of people on rooftops and there are prisoners that we cannot guard," Preval said.

Hanna had hovered off Haiti's coast since Monday, drowning crops in a desperately poor nation already struggling with food shortages. It also triggered widespread flooding in the neighboring Dominican Republic.

The Miami-based hurricane center said it was too early to say where Ike might go, after it churns through the Caribbean, but the storm has drawn the attention of energy companies running the 4,000 offshore platforms in the Gulf of Mexico that provide the United States with a quarter of its crude oil and 15 percent of its natural gas.

By late Wednesday, Josephine was swirling over the far eastern Atlantic about 465 miles west of the Cape Verde Islands. It was moving west but had begun to weaken, with top sustained winds dropping to 60 mph (95 kph).

(Additional reporting by Tom Brown in Miami; writing by Jane Sutton; editing by Todd Eastham and Philip Barbara)