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.

Forecasters are monitoring Tropical Storm Melissa, which is expected to become a “major” hurricane by the end of the weekend.

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