HAMILTON, Bermuda — Tropical Storm Bertha headed back out over open ocean and away from the U.S. mainland Tuesday after it battered Bermuda, knocking out electricity to thousands on the Atlantic tourist island.

It is the longest-lived July tropical storm in history, according to the U.S. National Hurricane Center. Bertha became the Atlantic season's first hurricane on July 7, but later weakened into a tropical storm. It was expected to re-strengthen into a hurricane by late Tuesday or early today, forecasters said.

Bertha was centered 315 miles northeast of Bermuda Tuesday afternoon..