On August 3, it was classified as a tropical depression, and the next day the system passed near Bermuda. The depression accelerated to the northeast, strengthening into a tropical storm on August 5. It intensified further due to baroclinity, or enhanced instability through different levels of the atmosphere caused by temperature and moisture gradients.[8] On August 6, a drilling rig about 230 mi (370 km) southeast of Newfoundland recorded sustained winds of 90 mph (140 km/h) with gusts to 126 mph (204 km/h) at an altitude of 325 ft (99 m); this suggested the storm attained hurricane status at 46° North, which is the northernmost location for a tropical storm to intensify into a hurricane.[6][4]