The erratic and slow-moving storm has killed at least three people in Haiti and a fourth person in the Dominican Republic, where another person remains missing.

The slow-moving storm was expected to drop torrential rain, up to 25 inches, on Jamaica. A similar forecast was issued for the southern regions of Haiti and the Dominican Republic.

Hurricane Melissa has likely begun rapid intensification in the Caribbean and is now forecast to be a Category 5 storm on Monday.

The storm was forecast to dump up to 25 inches of rain over Haiti, the Dominican Republic and Jamaica as it continues to strengthen this weekend.

Haiti is expected to see catastrophic flash floods and landslides early next week causing “extensive infrastructural damage and potentially prolonged isolation of communities.” The southwestern peninsula of Haiti, from the border of the Dominican Republic to Port-au-Prince, was placed under a hurricane watch and a tropical-storm warning.

Life-threatening flooding, landslides and storm surge are expected in Jamaica and southern Hispaniola as Melissa continues to strengthen.

Melissa, with maximum winds of 70 mph and stronger gusts, should attain hurricane status later Oct. 25 and become a major hurricane by Sunday, the National Hurricane Center said Saturday morning. A tropical storm becomes a hurricane when its winds reach 74 mph.

Hurricane Melissa is on track to rapidly strenghten and could become a major Category 5 hurricane, according to the NHC, Saturday, Oct. 25.

Melissa strengthened into a hurricane southeast of Jamaica and is set to rapidly grow, raising the risk for catastrophic flooding and wind damage across Jamaica and the Caribbean, where the storm has already killed at least four people.