After ravaging the Turks and Caicos Islands, Hurricane Ike headed toward the Bahamas, Cuba and the US Gulf Coast, as Tropical Storm Hanna continued to batter the US East Coast.
Ike, an "extremely dangerous" Category 4 storm, barrelled across the low-lying Turks and Caicos islands near the southern Bahamas in the predawn hours of Sunday, according to the US National Hurricane Center (NHC).
It was expected to careen past Florida into the Gulf of Mexico and toward Louisiana and its storm-battered city of New Orleans as early as Tuesday.
The center said the storm was bearing down on the Bahamas at 24 kilometer (15 miles) an hour. At 0900 hours GMT, its eye was located just 105 kilometers (65 miles) east of Great Inagua Island in the Bahamas chain.
An immediate concern was its effect on Haiti, where a humanitarian crisis was unfolding after flooding from Hanna left more than 500 people dead and thousands in desperate need of food, clean water and shelter.
With winds near 215 kilometers (135 miles) per hour, Ike was to churn just north of Haiti on its way to Cuba, but further flooding in Haiti is expected as the storm's outer rain bands were forecast to unleash torrential downpours on the country's vulnerable north-west coast. "These rains could cause life-threatening flash floods and mudslides over mountainous terrain," the center warned, predicting "some strengthening" of the storm.
It was an ominous forecast for the poorest country in the Americas, already reeling from the destruction inflicted by three storms in as many weeks, and where the United Nations has warned the death toll from Hanna's floods was "increasing hourly."
Some 650,000 people have been affected by the flooding, including 300,000 children, and the task of delivering crucial aid has been complicated by dismal transport conditions, according to UNICEF.
After Haiti, Ike was on course to plow into north-eastern Cuba late Sunday or Monday, another mountainous island nation recently battered by this season's devastating string of storms. Cuba-where Hurricane Gustav damaged or destroyed 140,000 homes in the west a week ago-was on high alert. "Almost our entire country is in the danger zone," Jose Rubiera, the head of Cuba's Insmet forecast agency, told Cuban television.
Meanwhile Tropical Storm Hanna raced across the US eastern seaboard Saturday, battering 1,600 kilometers (1,000 miles) of coastline with powerful waves and heavy downpours.
Hanna crashed into the border of North Carolina and South Carolina before dawn Saturday packing winds of 110 kilometers (70 miles) per hour before weakening as it moved up quickly along the coast. The storm churned over Virginia, but then gained strength slightly as Hanna streaked up the coast toward New England, the NHC said.
Early Sunday, Hanna was approaching the north-eastern US state of Massachusetts. In New York, the men's and women's finals of the US Open tennis championships were postponed by a day because of the storm.
The storm dumped up to eight inches (20 centimeters) of rain on the US capital Washington, according to the National Weather Service, and four to six inches (10 to 15 centimeters) across much of the east coast from North Carolina to New York state.
Hanna could also produce dangerous waves with a storm surge of one to three feet above normal tide levels, the hurricane center said. The storm was due to reach Canada's eastern province of Nova Scotia by midday Sunday.
Several southern US states have endured a battery of storms in recent weeks, including Tropical Storm Fay late last month and Hurricane Gustav this past week.
But officials expressed concern that people along the coast were not taking Hanna seriously. "The response is not what we would want it to be," Sam Hodge, emergency manager for Georgetown, South Carolina, told CBS News. "We feel there should be more people evacuating."
As Hanna pounded the US coast, Florida officials were closely monitoring the more formidable Hurricane Ike, with Governor Charlie Christ warning that Ike could strike southern Florida by Tuesday. "Ike has grown rapidly into a dangerous, powerful storm," Christ told a news conference.
"I urge all... Floridians to use the next few days to prepare. Our ability to prepare now will ensure everyone's safety later," he said. Densely populated south Florida, including the cities of Miami and Fort Lauderdale, has not been hit by a major hurricane since Hurricane Andrew in 1992 - the costliest natural disaster in US history until it was topped by Hurricane Katrina in 2005. The center of Ike was forecast to miss greater Miami-population 2.5 million-and rake over the Florida Keys to the south-west.