Tropical Storm Isaac forecast to become a hurricane in US
People in the Florida Keys are bracing themselves as Tropical Storm Isaac continues to gather strength and head towards the Southern coast of the United States.
Thousands of people have already lost power and the US Republican party cancelled the first day of its convention in Tampa.
Isaac has already battered parts of Cuba and Haiti, where it destroyed many of the shelters which are housing thousands of earthquake survivors.
Susan Powell from the BBC Weather Centre explained that the storm was likely to become a hurricane as it reaches Florida.