By David Adams
MIAMI, Aug 28 (Reuters) - Tropical Storm Erika threatened Haiti with heavy rain and strong winds on Friday as it swirled across the Caribbean but showed signs of petering out as it headed toward south Florida, the U.S. National Hurricane Center said.
At least eight people were confirmed dead on the island of Dominica, Prime Minister Roosevelt Skerrit said on Twitter, though rescuers still searched for others reported missing.
Due to some likely weakening over mountainous areas of Haiti and Cuba, Erika was no longer forecast to make landfall in the United States as a hurricane. Instead, it could lose tropical storm strength over the next two days, with winds falling below 40 mph (64 kph) as it moves over eastern Cuba, though heavy rain was still a concern.
"The forecast intensity has been significantly changed to show a much weaker cyclone," the hurricane center said in a late Friday afternoon advisory.
If Erika survives the mountains, it could regain intensity over the Straits of Florida and the Gulf of Mexico, it added.
"We're not quite prepared to rule out tropical storm impacts in Florida," the NHC 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.
The greatest risk over the next few days was heavy rain over impoverished Haiti's eroded hillsides, with up to 10 inches (25 cm) possible in some areas. This could cause "life-threatening flash floods and mudslides," the Miami-based NHC said.
As Erika neared Haiti on Friday, its sustained winds were still holding at 50 mph (80 kph), the NHC said.
So far the worst affected island was Dominica in the eastern Caribbean where the prime minister said in a radio broadcast that 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 lowered the number of confirmed fatalities from 12 to eight in a Twitter post. (Additonal reporting by Bill Cotterell in Tallahassee and Roberta Rampton in Washington; Editing by G Crosse and James Dalgleish)