Effects from the hurricane will occur outside that cone, he said, predicting some effects will be felt more than 100 miles from the storm's center.
The hurricane is about 1,230 miles out from Cape Fear, North Carolina, and moving west at about 13 mph.
The latest forecast from the National Hurricane Centre said the storm winds have reached 75mph (120kph), which means it is now at hurricane strength.
A Category 4 hurricane with 130 miles per hour winds is bearing down on the US East Coast, bringing a risk of devastating floods.
A tracker map from the center on Monday forecast the hurricane making landfall in the Carolinas Thursday morning, and expected the storm to continue through Saturday morning, when it will have weakened to a tropical depression.More news: Nicki Minaj throws shade at Cardi B after Fashion Week fight
"It's nearly certain there will be some impact on Charlotte, but it depends on the track", meteorologist Jake Wimberley said from the weather service's office in Greer, S.C. The office forecasts for the western Carolinas including Charlotte.
At the same time Florence is expected to make its landfall, another storm, Hurricane Isaac, is forecast to move across the Lesser Antilles and into the eastern Caribbean Sea.
The storm's potential path also includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous eastern hog farms that store animal waste in massive open-air lagoons.
North Carolina Gov. Roy Cooper said his state was "in the bullseye" of the storm and urged people to "get ready now".
At present, Hurricane Florence is about 1,400 miles of the coast of Charleston, which is almost as far away as the city is from the Rocky Mountains.
Cooper also said power outages could be widespread and he encouraged people to be proactive in preparing for stretches with no electricity.More news: Hurricane Florence strengthens to Category 4, heads toward Carolinas
A Category 4 hurricane with 105 miles per hour winds is bearing down on the US East Coast, bringing a risk of devastating floods - and there are two more hurricanes behind it.
The National Hurricane Center warned that it would likely bring devastating storms and floods to those regions.
The governor said residents should prepare for ocean surge, strong winds, and inland flooding.
Troops have received ready to deploy orders for Virginia, South Carolina, and North Carolina.
Mr Roker told TODAY viewers: 'We're at the peak of the tropical Atlantic hurricane season, and right now we've got three hurricanes, Helene, Issac and Florence. After passing the Cabo Verde Islands the system was not expected to pose a direct threat to land for at least several days.
Florence now is a category 1 hurricane as of the 5 p.m. advisory.More news: As Trump fumes over leaks, Woodward pushes back on criticism