Helene is now 2,065km south-southwest of the Azores in the Atlantic and Met Éireann said the storm would approach the south coast by Tuesday.
Tropical Storm Helene is already transitioning to an extra-tropical cyclone southwest of the Azores Islands. It will continue to move to the west and away from the V.I. during the overnight hours. "A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations hard or unsafe". The hurricane will weaken as it moves over cooler water, and is expected to be downgraded from hurricane to tropical storm status before making the transition to post-tropical storm on Sunday.
Isaac is expected to reach the islands, which remain under a tropical storm warning, by Thursday afternoon and cross the Caribbean through Saturday.
Forecasters said Isaac will bring several inches of rain to some locations and possibly life-threatening surf conditions. That's out in open ocean, where waves are much larger than those reaching the coast as storm surge.
Maui Mayor Alan Arakawa said he hoped the effects of the storm would be limited.
With the storm churning across the Atlantic with 140 miles per hour winds, hurricane watches and warnings include the homes of more than 5.4 million people on the East Coast.More news: Airstrikes batter Syria’s last rebel stronghold after cease-fire bid fails
Maximum sustained winds remain near 60 miles per hour (95 km/h) with higher gusts.
The center of the Category 4 Hurricane, still swirling with top winds of 130 mph (215 kph), was about 530 miles (855 kilometers) southeast of Cape Fear, North Carolina, approaching the coast at 17 mph (28 kph).
Most of North Carolina is expected to receive 10 inches of rain, with two feet expected along the coast.
"Cloudiness and showers associated with a trough of low pressure over the south-central Gulf of Mexico have decreased since yesterday and the Air Force reconnaissance plane scheduled to investigate the system for today will likely be canceled", said the NHC on September 12.
Meteorologists are also keeping an eye on yet another tropical disturbance that's spinning in the western Gulf of Mexico.
Current guidance suggests the potential for warning level winds and perhaps rain with the system.