Melissa rapidly intensified going into Sunday morning and is now a Category 4 hurricane with 140 mph winds. The US National Hurricane Center expects it to strengthen into a rare Category 5 hurricane on Sunday night or early Monday.

Tropical Storm Melissa has strengthened into a hurricane and is expected to become a major hurricane by the end of the weekend, the U.S. National Hurricane Center said on Saturday.

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