The centre in Miami said Monday that Humberto had strengthened and could become a major hurricane by Tuesday night or Wednesday morning. The Bermuda Weather Service has issued a tropical storm watch for the island.
Humberto was about 670 miles west of Bermuda Monday evening with maximum sustained winds of 90 mph. The storm was moving east-northeast at 7 mph.
Over the next few days, swells generated by Humberto will roil the northwestern Bahamas coast as well as the southeastern US Atlantic coast from central Florida to North Carolina. Such swells could pose life-threatening surf and rip current conditions to swimmers and surfers.