The Caribbean islands of Haiti, the Dominican Republic and Cuba scrambled Thursday to prepare for damaging winds and rains as tropical storm Isaac whipped up three-meter waves and threatened to develop into a hurricane as it neared land.

According to the latest report from the Miami-based National Hurricane Center (NHC), issued at 2 pm local time (1800 GMT), the ninth storm of the season was located some 445 kilometers southeast of Santo Domingo, the capital of the Domican Republic, which shares the island of Hispaniola with Haiti, and was moving west-northwest at 24 kilometers per hour, with maximum sustained winds of 65 kph.

Forecasters predicted Isaac could turn into a category 1 hurricane as it nears Hispaniola Friday, then weaken as it moved overland. Eastern Cuba was also expected to fall in Isaac's path. Category 5 hurricanes are the deadliest.

Haitian Prime Minister Laurent Lamothe called the country's disaster prevention agencies to an emergency meeting to decide what steps to take should Isaac rip through Haiti.

Lamothe told the meeting he intended to mobilize all available government resources to limit the effects of the storm, and called on the population to heed the instructions of authorities. A nationwide maximum red alert has been in effect since late Wednesday in case of floods and mudslides.

In the neighboring Dominican Republic, classes were suspended and disaster agencies put on alert as newly-instated President Danilo Medina met with the National Emergency Commission (CNE) to examine contingency plans.

A red alert was called for 21 provinces and a medium-level yellow alert for the remaining 11 to prepare for Isaac, which was already lashing the eastern tip of the island since dawn Thursday.

Authorities also called for a voluntary evacuation of low-lying zones as a preventive measure, while public hospitals nationwide prepared for a spike in emergency care.

Flights from Santo Domingo to San Juan, Puerto Rico, where residents were also bracing for the effects of Isaac, were suspended, but all others were operating as usual.

The National Meteorological Office (Onamet) warned Isaac could dump as much as 100 to 250 millimeters of rain around the country starting Thursday night.

In Cuba, meteorologists were closely monitoring the trajectory and evolution of the tropical storm.

At the National Meteorological Institute (Insmet), the director of the forecast center, Jose Rubiera, said models predicted the storm would turn west-northwest, passing over the southern Dominican Republic on Friday afternoon.

He added that if Isaac crossed directly over Dominican territory and part of Haiti, it would weaken by the time it reaches eastern Cuba Saturday.

Experts have forecast between nine and 15 tropical storms, and four to eight hurricanes during this season, which runs from June through November.

In Latin America, Mexico and the Dominican Republic both reported several deaths from previous tropical storm Ernesto.