Storm clouds over Haiti
The authorities in Haiti are urging thousands of people to leave temporary camps because of the approaching Hurricane Tomas.
It's already raining heavily there, and forecasters warn that Tomas could destroy many of the makeshift tented homes where tens of thousands of people have been living since an earthquake in January.
But many are refusing to leave, saying they have nowhere else to go.
Aid agencies are rushing to get emergency shelters ready before Tomas, which has already killed fourteen people in Saint Lucia, arrives.
By Friday morning, Hurricane Tomas was packing winds of 80mph (130 kph), making it a Category One storm.
It was expected to gain in strength as it moves north-east.
The US National Hurricane Centre says the centre of the hurricane will pass near western Haiti.
Forecasters are warning of the danger of flooding and mudslides. Health workers fear heavy rain will exacerbate Haiti's cholera epidemic.
Also in the firing line
Jamaica, Cuba and the Turks and Caicos are also in Tomas's sights.
In Jamaica, hurricane shelters were opened to accomodate people whose homes were deemed at risk.
Just over a month ago in Jamaica - on 29 September - a number of people were killed in flooding caused by Tropical Storm Nicole.
As the storm makes it way across western Haiti, through the Mona Passage between Cuba and Haiti, eastern Cuba was also expected to experience heavy rainfall.
In the Turks and Caicos Islands, which is likely to get a direct hit after the storm passes Haiti, officials have put the British territory on hurricane warning.
'Protect your lives'
In Haiti, aid agencies are rushing to get emergency shelters ready before Tomas, which has already killed 14 people in Saint Lucia, arrives.
According to the US National Hurricane Centre, Tomas should intensify over the next 24 hours and then lose strength by the end of the weekend.
Forecasters warn Hurricane Tomas could destroy many of the makeshift tented homes where 1.3m people have been living since an earthquake in January.
Haiti's leaders have been calling for mass evacuations from the tent cities.
"My sisters and brothers, leave the zones that are at risk, I beg of you," Prime Minister Jean-Max Bellerive urged in a television address.
Those staying in the camps are making their shelters as strong as possible "There will be rain and wind throughout the country. Don't be stubborn. Leave if you are in a fragile shelter."
President Preval had earlier pleaded with people to "protect" their lives. But he acknowledged that the authorities did not "have enough places [on buses] to move everyone".
The BBC's Laura Trevelyan in the capital, Port-au-Prince, says few refugees have heeded the government warning, although mothers and babies have been evacuated from an exposed camp near the mountains.
"We haven't taken precautions. We are in God's hands," one woman, Ave Lise Mesila, told Reuters news agency from her tent.
Stefano Zannini, Medecins Sans Frontieres' head of mission in Haiti, described the situation as "precarious".
"It is the third big problem people here have had to deal with this year," he told the BBC.
Fear and confusion
The NHC has warned of hurricane conditions - winds of 119km/h (74mph) or greater - for Haiti, the south-eastern Bahamas, the Caicos Islands and the Cuban province of Guantanamo.
It also issued a tropical storm warning for Jamaica and the Cuban provinces of Santiago de Cuba and Holguin.
Many earthquake survivors worried that the authorities were trying to permanently move them out.
"We are upset because they have not told us where we are going," Domarcand Fenel, the head of a committee of camp residents, told Reuters. "People believe they want to expel us."
Doctors have warned that torrential rain could flood sanitary installations and contaminate drinking water, worsening a cholera epidemic in the country.
On Wednesday health officials said there had been a 40% jump in the number of new cholera cases and the death toll was 442, with 105 more deaths since Saturday.