Hurricane Melissa maintained its powerful Category 4 strength on Sunday as it drifted slowly toward Jamaica, forecast to bring “catastrophic” flash flooding and landslides to the Caribbean nation.

U.S. forecasters issued a hurricane warning for Jamaica Saturday as Storm Melissa reached hurricane strength, threatening catastrophic flooding in the northern Caribbean.

“If those rains were to occur, you’re talking about catastrophic flooding potential,” said Jamie Rhome, the center’s deputy director.