HAVANA (Reuters) - Hurricane Ike charged toward Cuba and the Gulf of Mexico as a ferocious Category 4 storm on Saturday, while Tropical Storm Hanna drenched the U.S. Atlantic coast after barreling ashore in the Carolinas.
Ike's top sustained winds reached 135 miles per hour (215 kph), making it an "extremely dangerous" Category 4 on the five-step Saffir Simpson scale of hurricane intensity, the U.S. National Hurricane Center said.
Ike alternately weakened and strengthened but was likely to remain a "major" hurricane of at least Category 3 as it hit Cuba, the forecasters said.
The densely populated Miami-Fort Lauderdale area in south Florida was not out of the line of fire, and visitors were ordered to flee the vulnerable Florida Keys island chain starting on Saturday.
But computer models indicated Ike was likely to sweep into Cuba late on Sunday, presenting a severe threat to sugar cane fields, the tourist hotels of Varadero and the crumbling colonial buildings of Havana.
The storm might then curve into the Gulf of Mexico in the wake of this week's Hurricane Gustav, plowing toward an area that produces a quarter of domestic U.S. oil, and slamming ashore near New Orleans, which was swamped and traumatized by Hurricane Katrina three years ago.
Katrina was a Category 3 when it struck near New Orleans on August 29, 2005, swamping the city and killing 1,500 people on the U.S. Gulf Coast.
The deeper Ike goes into Cuba, the weaker it will be once it re-emerges over the Gulf of Mexico early next week, the hurricane center said.
"By day four, Ike is forecast to emerge back over open waters in the southeastern Gulf of Mexico," the agency said. "Global models suggest the environment will be favorable for strengthening and the ocean should be plenty warm."
Alerts went up across eastern Cuba on Saturday as residents shivered at the prospect of another major storm a week after Hurricane Gustav devastated parts of western Cuba.
In Havana, residents lined up at gas stations and searched stores for candles, crackers and canned goods after a forecaster warned on state television that "almost the entire country is in the danger zone."
"It looks like this year we will have no respite," Eduardo Gonzalez said from eastern Santiago de Cuba, "and if it continues like this we will have to live out the hurricane season in the shelters."
Hanna did not reach hurricane strength before sloshing ashore over North and South Carolina overnight after killing 500 people in Haiti with torrential rain.
Gonaives Police Commissioner Ernst Dorfeuille said floods had killed more than 495 people in that northern port city, although officials in the capital put the official tally lower.
"The number of people killed could even go beyond 500, but for the time being the official death toll for the country is 165, including 119 for Gonaives and its surroundings," said Alta Jean-Baptiste, director of the civil protection agency.
Hanna was forecast to move rapidly northeast along the U.S. East Coast, bringing heavy rains to the mid-Atlantic states and southern New England. More than 5 inches of rain fell in Raleigh, North Carolina, and a steady downpour drenched the U.S. capital, Washington, and neighboring Virginia and Maryland.
"We have been incredibly fortunate," North Carolina emergency management spokeswoman Jill Lucas said. "We have had no significant damage. We have had some trees down and local flooding but nothing significant."
Hanna was about 40 miles west-northwest of Ocean City, Maryland, by 5 p.m. EDT (2100 GMT) and moving northeast at 28 mph (44 kph), the hurricane center said. Its top sustained winds had dipped to 50 mph (85 kph).
Ike was far more threatening than Hanna as it charted a course that would take it through the Turks and Caicos islands and southeastern Bahamas toward eastern Cuba. It was around 90 miles east of Grand Turk Island.
Once in the Gulf of Mexico it might find deep warm water to allow it to grow bigger and stronger, although Hurricane Gustav may have stirred up colder water from the depths before crashing into Louisiana on Monday.
In southeast Florida, up to 1.3 million people could be forced to evacuate if the storm turns north. State and local officials urged Miami residents not to be complacent.
In the low-lying Florida Keys, visitors were ordered out on Saturday and residents were told to evacuate on Sunday along the lone road linking the island chain to the mainland.
Former Key West Mayor Jimmy Weekley, owner of Fausto's Market, said the store had a run on water on Friday but business returned to normal on Saturday.
"I think people are seeing the new hurricane track and are not as concerned as they were yesterday," he said.
John Vagnoni, owner of the Green Parrot Bar, said there would be no hurricane party there.
"We don't do a hurricane party, per se, at the Parrot," Vagnoni said. "Let's take care of our own houses, be safe and then, afterward, there will be plenty of time to have a party. I'd much rather have a survivors' party."
Tropical Storm Josephine dissipated far out in the Atlantic without ever threatening land.
Additional reporting by Michael Haskins in Key West; Writing by Jane Sutton and Michael Christie; Editing by Peter Cooney