The US National Hurricane Center (NHC) said that Tropical Storm Isaac formed in the Atlantic Ocean on Tuesday and was expected to strengthen into a hurricane later this week as it moves on projected path across most of the Caribbean. The storm had top winds of 64 km per hour and is forecast to become a hurricane by Thursday as it approaches Puerto Rico, NHC said. NHC’s computer forecast models show the storm moving as a hurricane across parts of Puerto Rico and then the Dominican Republic, Haiti, Jamaica and a large swath of Cuba. The centre added that it was too early to know whether Isaac would threaten energy interests clustered in the Gulf of Mexico.