KEY WEST, Florida (Reuters) - Hurricane Ike charged toward Cuba and the Gulf of Mexico as a ferocious storm on Saturday while Tropical Storm Hanna drenched the U.S. Atlantic coast after barreling ashore in the Carolinas.

The densely populated Miami-Fort Lauderdale area in south Florida was not out of the line of fire from Ike, a "major" Category 3 hurricane, and visitors were ordered to flee the vulnerable Florida Keys island chain from Saturday.

"We're not out of the woods by any stretch of the imagination," Miami-Dade County Mayor Carlos Alvarez said.

Computer models indicated Ike was likely to target Cuba as a Category 3 hurricane on the five-step Saffir-Simpson intensity scale, presenting a severe threat to the crumbling colonial buildings of Havana and tourist hotels at Varadero.

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.

The deeper Ike goes into Cuba, the weaker it will be once it re-emerges over the Gulf of Mexico early next week, the U.S. National Hurricane Center said.

"By day four, Ike is forecast to emerge back over open waters in the southeastern Gulf of Mexico," the Miami-based agency said. "Global models suggest the environment will be favorable for strengthening and the ocean should be plenty warm."

Hanna, meanwhile, did not reach hurricane strength before sloshing ashore between North and South Carolina overnight after killing 500 people in Haiti through torrential rain.

It was forecast to move rapidly northeast along the East Coast over the weekend, bringing heavy rains and floods 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 capital Washington D.C.

"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." POWER OUT FOR THOUSANDS Almost 60,000 homes lost power at one point, but by mid-afternoon that was down to 39,000, Lucas said. Hanna was about 55 miles north-northwest of Norfolk, Virginia, by 2 p.m. EDT and moving to the northeast at 25 miles per hour, the hurricane center said. Its top sustained winds had dipped to 50 mph.

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, where it was expected to pummel a long stretch of coastline.

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.

Ike was located around 135 miles east of Grand Turk Island, and its top sustained winds had climbed back to 115 mph after briefly dipping.

Ike had been an extremely dangerous Category 4 storm, but was no longer projected to regain that strength before hitting Cuba, which has barely had time to recover from a disastrous Category 4 blow from Hurricane Gustav a week ago.

Instead, it was likely to strike the communist-ruled island as a Category 3 hurricane, the hurricane center said. Category 3 and higher storms are known as "major" hurricanes and cause the most damage. 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.

South Florida, where up to 1.3 million people could be forced to evacuate, was preparing for Ike. State and local officials in Miami urged residents not to be complacent.

"We are still recovering as you are aware from Tropical Storm Fay but we must and we will handle any storm that may come our way," Florida Gov. Charlie Crist said.

In the low-lying Florida Keys, visitors were ordered out on Saturday and residents were told to evacuate on Sunday.

Former Key West Mayor Jimmy Weekley, owner of Fausto's Market, said residents appeared more concerned about Ike on Friday.

"Friday we had a run on water," Weekley said. Saturday was almost a normal business day, he said. "I think people are seeing the new hurricane track and are not as concerned as they were yesterday. Our shelves are stocked, and we have a lot of fresh fruits and vegetables and canned goods."

John Vagnoni, owner of the Green Parrot Bar, said there would not be a hurricane party there.

"We don't do a hurricane party, per say, 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, meanwhile, dissipated far out in the Atlantic, knocking out the weakest of three storms that followed Gustav's rampage through the Caribbean to Louisiana.

More Information from NOAA:

www.nhc.noaa.gov

Photo Courtesy NOAA

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