Mississippi Governor Phil Bryant declared a state of emergency Sunday as his state and three others along the U.S. Gulf Coast prepared for Tropical storm Isaac.

Weather forecasters say tropical storm-force winds could hit the Mississippi coast Monday night.

National Hurricane Center Director Rick Knabb told Bryant on a conference call that forecasters expect Isaac to strengthen into a hurricane, raising waters by 1.8 to 3.5 metres. Coastal areas could also get 30 to 40 centimetres of rain and be subject to tropical storm-force winds for as long as 36 hours beginning late Monday.

Knabb said forecasters are still having a hard time predicting where Isaac's centre will make landfall. It could come ashore Wednesday morning, seven years to the day after Hurricane Katrina killed hundreds and caused billions of dollars in damage in Mississippi and neighbouring Lousiana.

Bryant, at a news conference Sunday evening, said Isaac seems to be on the same track and offers the same possibility for storm tides and damage to inland parts of the state.

The Republican National Convention will open in Tampa as planned Monday, but official events have been postponed because of the storm.

RELATED: Republican convention, Florida brace for Isaac 

Louisiana Governor Bobby Jindal called a state of emergency and suggested that people begin leaving low-lying parts of the state. He also said he may skip a speaking engagement later this week at the Republican National Convention in Tampa unless the threat to his state subsides.

Alabama Governor Robert Bentley has also canceled his trip to the convention because of Isaac. An emergency declaration was also issued in Mississippi by Gov. Phil Bryant amid concerns of storm surge threatening low-lying areas.   Florida Governor Rick Scott said at a news conference Sunday evening that only minor damage was reported from Isaac.

Even before reaching hurricane strength, Isaac caused considerable inconvenience, with more than 550 flights canceled at Miami International Airport and about 150 from Fort Lauderdale's airport. There were scattered power outages from Key West to Fort Lauderdale affecting more than 16,000 customers, and flooding occurred in low-lying areas.

Residents brace for possible hurricane

A steady line of cars moved north along the Overseas Highway, the only road linking the Keys, while residents boarded up windows, laid down sandbags and shuttered businesses ahead of the approaching storm.

Even Duval Street, Key West's storied main drag, was subdued for a weekend, though not enough to stop music from playing or drinks from being poured.

Republican convention shortened

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Among the highest-profile potential targets of the storm was the Republican National Convention, set to begin Monday in Tampa.

Forecast models show Isaac likely won't hit Tampa head-on, but Republican officials said the convention would only convene briefly on Monday as a precaution then immediately recess until Tuesday afternoon, when the storm should have passed

Read more.

"We'll just catch every place that's open," said Ted Lamarche, a 48-year-old pizzeria owner visiting Key West to celebrate his anniversary with his wife, Deanna. They walked along on Duval Street, where a smattering of people still wandered even as many storefronts were boarded up and tourists sported ponchos and yellow slickers.

"Category None!" one man shouted in a show of optimism.

Authorities have warned tourists to head for the mainland.  

When it hits, winds will be "enough to knock you over," National Hurricane Center spokesman Dennis Feltgen said.

The Keys braced for a storm surge of up to 1.2 metres, strong winds and the possibility of tornadoes. The island chain's two airports closed Saturday night and volunteers and some residents began filing into shelters.

"This is a huge inconvenience," said Dale Shelton, a 57-year-old retiree in Key West who was staying in a shelter.

The hurricane centre said the storm, which was swirling off the northern coast of Cuba overnight, was expected to move near or over the Florida Keys later in the day or Sunday night. Isaac was then forecast to move over the southeast Gulf of Mexico on Monday.

Isaac leaves trail of destruction across Caribbean

The storm's centre made landfall Saturday near the far-eastern tip of Cuba, downing trees and power lines. In the picturesque city of Baracoa, the storm surge flooded the seaside Malecon and a block inland, destroying two homes. 

There has been a reported total of 10 deaths for the island of Hispaniola, which is shared by Haiti and Dominican Republic. The scale of devastation was less than many people had feared.

But the capital and countryside of disaster-prone Haiti did suffer sporadic flooding, fallen poles and scores of toppled tents that housed people who lost their homes in the massive 2010 earthquake.

Joseph Edgard Celestin of Haiti's Civil Protection Office offered few details on the storm-related deaths, but said one man was swept away as he tried to cross a river in a village in the country's north.

Haiti's Civil Protection Office said in a separate report that a 51-year-old woman was killed in the southern coastal town of Marigot after a tree fell on her home. A 10-year-old girl was killed in the village of Thomazeau after a wall collapsed on her.

In neighbouring Dominican Republic, police reported that two men were swept away by flooded rivers that burst their banks. One victim was identified as Pedro Peralta, a former mayor in Villa Altagracia, a town northwest of the capital of Santo Domingo. His body was recovered Sunday by rescuers on the banks of the Haina River.

Another male victim, whose identity was not disclosed, was swept away by the Yaguaza River, Dominican police said.

Across Haiti, the number of people evacuated due to flooding rose over the weekend. More than 14,000 people had left their homes and another 13,500 people were living in temporary shelters until Saturday night, the Civil Protection Office reported. Some 8,400 evacuees were in the country's western department, the most populous and where the capital of Port-au-Prince is located.  

"All our children are sleeping in the mud, in the rain."  —Cite Soleil resident Jean-Gymar Joseph

"From last night, we're in misery," said Cite Soleil resident Jean-Gymar Joseph. "All our children are sleeping in the mud, in the rain."

"They promised they were going to build us a sturdy home and it never came," Jean-Robert Sauviren, an unemployed 63-year-old father of six said as he stood barefoot in the water and held aloft his arms. "Maybe we don't deserve anything."