Hundreds of thousands of Haitians living in squalid makeshift camps hunkered down Wednesday as lashing rain and wind from the outer bands of Tropical Storm Emily hit the quake-stricken country.
US weather experts warned of "torrential rain" and "life-threatening flash floods and mud slides" once the brunt of Emily reaches Haiti early Thursday, compounding the misery for the impoverished Caribbean nation still recovering from a January 2010 earthquake.
Some 300,000 Haitians still living in makeshift camps almost 19 months after the quake may have to battle up to 20 inches (50 centimeters) of rain cascading down muddy, denuded hillsides.
Haitian officials have raised a red alert and called for the evacuations of tent cities at risk, many perched on hillsides long since stripped bare of any trees, chopped down to use as fuel and building materials.
Authorities were spreading the word and "are asking people in refugee camps... to evacuate vulnerable locations," said Haiti's civil defense chief Alta Jean-Baptiste.
Haiti's weather service chief Ronald Semelfort warned Emily would be "a great danger for the country still fragile from the January 2010 earthquake."
At 2100 GMT, the center of Emily was some 203 miles (326 kilometers) south-east of the Haitian city of Les Cayes, the Miami-based National Hurricane Center reported.
The storm was packing winds of nearly 50 miles (85 kilometers) per hour, with higher gusts, and was moving at a speed of nearly 14 miles (22 kilometers) per hour.
"On this track, the center of Emily will cross the southwestern peninsula of Haiti early Thursday and then over extreme eastern Cuba Thursday night," the NHC said.
Emily is forecast to dump between six and 12 inches (15 and 30 centimeters) with isolated amounts of up to 20 inches (51) possible over Haiti and its wealthier eastern neighbor, the Dominican Republic, with which it shares the island of Hispaniola, the NHC said.
"Some weakening is possible as Emily interacts with the high terrain of Haiti and eastern Cuba," the NHC said. "Some re-strengthening is possible when the cyclone moves over the Bahamas."
Coastal areas were warned of a storm surge which will raise water levels by one to two feet and be "accompanied by large and dangerous waves."
Shipping was banned along Haiti's the southern coast as the storm approached,, and Semelfort said "all Haiti's regions will be affected by the tropical storm Emily."
Haiti is still recovering from the devastating 2010 quake, which killed an estimated 225,000 people. The country has also been battling an outbreak of cholera, which caused 5,506 deaths and 363,117 diagnosed cases.
A team of Cuban doctors in Haiti were on standby Wednesday to prevent any further outbreaks of the water-borne disease.
"People living in unsafe housing will be the worst affected if flooding hits," said Harry Donsbach, the earthquake response director in Haiti for the Christian charity group World Vision.
"Landslides are of course a threat, but even simply heavy rain has the potential to worsen the volatile sanitation conditions in camps, which, with cholera still prevalent in Haiti, is a serious concern," Donsbach said in a statement.
In the Dominican Republic, a maximum red alert has been sounded across six provinces, and all water and outdoor leisure activities suspended.
Mandatory evacuations were declared in a dozen villages near dams, and Dominican officials urged residents to take precautions in other areas.
"Residents in high-risk areas, who live next to rivers, streams and creeks... should take precautions and be aware of the recommendations of the relief agencies," the government's office of emergency services said.
The tropical storm warning was also in effect for eastern Cuba, the central Bahamas, and the Turks and Caicos islands, US weather experts said.
In Cuba, the national Institute of Meteorology said to expect heavy rain from Emily in the far eastern part of the island by Thursday afternoon.
In the Pacific Ocean, meanwhile, Hurricane Eugene strengthened to a category four storm far off Mexico's western coast, but was heading away from land towards the north-west and into the open sea.