Ahead of Helene is Hurricane Florence, a Category 4 storm that is projected to make landfall near the Carolinas later Thursday.
National Weather Service officials in Honolulu urged residents to remain careful, noting that the difference between a Category 1 hurricane and a tropical storm is just 5 miles per hour wind speed. "Be careful!" he tweeted.
He says the time to flee Hurricane Florence is now.
"Florence is forecast to be an extremely risky major hurricane as it approaches the USA coast", the NHC said.
"It wants to get stronger", he said of the storm. "Don't plan to leave once the winds and rains start".
The storm has a raincloud band that's 900 kilometers wide - and it's coming alongside monsoon rains, creating risks for flash floods and landslides.
Hurricane Florence's winds start to rake North Carolina coast
The city said early Friday that two out-of-state FEMA teams were working on swift-water rescues and more teams were on the way. At least 12,000 people had taken refuge in 126 emergency shelters, Governor Cooper said, with more facilities being opened.
Hurricane Florence is now generating waves up to 83 feet, almost double the height measured on Tuesday. The storm is packing top winds of 70 miles per hour while tracking to the west at 17 miles per hour.
Shared content for Virgin Islands Source and St. John Tradewinds. However, while the hurricane hasn't strengthened in terms of peak winds, the inner-core and outer wind fields have continued to expand, resulting in an increase the cyclone's total energy, which will create a significant storm surge event.
Isaac is forecast to move into the eastern Caribbean Sea on Thursday, and then move across the eastern and central Caribbean Sea through Saturday, the hurricane center said. Mandatory evacuations have been issued for much of the SC and North Carolina coastline.
Residents on the Carolina coast are finding empty gas pumps and depleted store shelves as they flee a potentially devastating blow from Hurricane Florence.
Some fluctuation in wind speeds are expected, and weakening forecast Thursday, but it's still expected to be a fierce storm triggering unsafe flooding. A steady stream of vehicles filled with people and belongings is moving inland.
On the current projected track the centre of this system is forecast to pass between 100 and 150 miles (160 to 240 km) north of Barbados early on Thursday morning.