Behind Isaac, Hurricane Helene is gaining strength, with wind speeds of over 105 miles per hour (170 kilometres per hour) as of Monday afternoon.
On Sunday, Florence reached sustained winds of at least 74 miles per hour to be classified a hurricane.
The category 4 hurricane is now moving to the west at 13 miles per hour and is expected to begin a turn to the northwest by late Wednesday.
Florence's centre was expected to move over the Atlantic Ocean between the Bahamas and Bermuda on Tuesday and Wednesday before approaching North and SC on Thursday.
At this statistical height of the Atlantic hurricane season, Florence was being trailed on east-to-west paths by two hurricanes, Helene and Issac.
"There is an increasing risk of life-threatening impacts from Florence: storm surge at the coast, freshwater flooding from a prolonged and exceptionally heavy rainfall inland and damaging hurricane-force winds", a 5 a.m. advisory said. Emergency officials say they're keeping a close eye on the forecast and where to move resources to respond to the storm.
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Next is a different look at the hurricane's projected path. Keep in mind that this map has an interactive component that you can view here.
Here in North Carolina there's a growing potential many will deal with destructive winds, devastating flooding and possible tornadoes.
- Both North and SC are under states of emergency as Hurricane Florence looks to strike the Carolina coast.
Helene - now just southeast of the Cabo Verde islands off the African coast - had winds of 136km/h, and was expected to turn northwest and then north into the open Atlantic by midweek, the NHC said.
In Guam, Typhoon Mangkhut - a Category 4 storm - narrowly missed dealing a direct blow to the island.
Officials in North Carolina have already issued mandatory evacuation orders for coastal Dare County and Hatteras Island. Even in areas far from the coast, he added, parts of North Carolina and Virginia could see rain totals of 10-15 inches over the next seven days.
The US military said it was sending an advance team to Raleigh, North Carolina, to coordinate with state and local authorities. "Whipping out store shelves of water and other supplies". "These tropical storms and hurricanes are very risky".