Tropical Storm Erika was soaking Haiti with heavy rain and strong winds on Friday as it swirled across the Caribbean but showed signs of losing steam as it headed toward south Florida, the U.S. National Hurricane Center (NHC) said.
Twenty people were confirmed dead on the island of Dominica, Prime Minister Roosevelt Skerrit said in an address carried on television and online late Friday. Rescuers were still searching for others reported missing.
Erika was no longer forecast to make landfall in the United States as a hurricane due to some likely weakening over mountainous areas of Haiti and Cuba. Instead, it could lose tropical storm strength by Saturday, with winds falling below 40 miles per hour (64 kph) as it moves over eastern Cuba, although "very heavy rainfall" was a concern.
"The forecast intensity has been significantly changed to show a much weaker cyclone," the hurricane center said in a Friday evening advisory.
Erika could regain intensity over the Straits of Florida and the Gulf of Mexico if it survives the mountains, the NHC said.
"We're not quite prepared to rule out tropical storm impacts in Florida," it said.
Florida Governor Rick Scott declared a state of emergency on Friday, noting the storm could travel "up the spine of Florida" from Sunday into next week.
Scott said the Tampa area on Florida's Gulf Coast was a major flood concern due to saturation from rain this month.
Forecasters have described Erika, the fifth named storm of the Atlantic hurricane season, as unusually hard to predict due to disruption from wind patterns and interaction with land, which weakens a storm, as well as warm water, which adds energy.
Meteorologist Jeff Masters said the mountainous island of Hispaniola, which Haiti shares with the Dominican Republic, "has saved us so many times in the past," thanks to its 10,000-feet (3,000-meter) peaks.
"It's probably saved thousands of lives in South Florida over the years," he said.
However, heavy rain over impoverished Haiti's eroded hillsides, with up to 10 inches (25 cm) possible in some areas, could cause "life-threatening flash floods and mudslides," the Miami-based NHC said.
Erika's sustained winds dropped to 45 mph (72 kph) as it moved over Haiti's capital, Port-au-Prince, on Friday night, the NHC said.
Haiti's government warned those who live by ravines, rivers and the coast to use extreme caution if they go outdoors. Mayors and local authorities were told to open schools and public buildings as makeshift shelters.
Dominica in the eastern Caribbean was the worst-affected island so far. The prime minister said swollen rivers and rain-triggered landslides had swept away homes, roads and bridges.
Some communities were cut off on the small, mountainous island with a population of about 72,000.
Skerrit said 20 people had died and several others were still missing. He described the destruction as "monumental."
