Hurricane Melissa strengthened into a major Category 4 hurricane, with the possibility of intensifying to a Category 5 storm Sunday night, unleashing torrential rain and threatening to cause catastrophic flooding in the northern Caribbean,

The slow-moving Melissa strengthened into a major Category 3 hurricane late Saturday as it threatened catastrophic flooding in the northern Caribbean.

Already, dozens of water supply systems are offline in the Dominican Republic, affecting more than 500,000 customers, with downed trees and traffic lights causing disruption.