Tropical Storm Florence is expected become a “major hurricane” Monday as it continues to approach the southeastern U.S. East Coast.

In its 11 p.m. EDT advisory, the National Hurricane Center said “a rapid phase of intensification” was expected to begin Sunday.

Florence is expected to travel between Bermuda and the Bahamas on Tuesday and Wednesday before approaching the southeastern U.S. coast on Thursday.

The Miami-based weather center says Florence’s maximum sustained winds are estimated to be 70 mph (110 kph). The storm is centered about 790 miles (1,270 kilometers) southeast of Bermuda and moving west at 6 mph (9 kph).