VERIFY QUESTION

Florence slammed into the North Carolina coast and pummeled eastern communities with strong winds and torrential rain. One of the biggest threats and deadly dangers didn't arise until days later -- at least 16 flood-prone rivers were about to crest at record levels. Why, sometimes days after the storm leaves and rain subsides, do rivers crest?

VERIFY SOURCE

To VERIFY, we consulted Good Morning Show meteorologist Ed Matthews.

VERIFY PROCESS

Matthews first explained what it means when rivers crest.

"When rivers reach their peak of flood stage level," he said. After the crest, waters start to recede.

He used the Cape Fear River as an example. The Cape Fear River's flood stage is 35 feet, but it crested Tuesday at 62 feet!

The Haw River and Deep River, in the Triad's back yard, come together in Chatham County. They feed into the Cape Fear river as tributaries.

Consider that the Cape Fear River is I-40 -- a major interstate leading to Raleigh. All the exits -- Burlington, Graham, Mebane -- along the way are dumping cars into I-40, the same as tributaries are dumping water into the Cape Fear river. By the time the route -- or the river -- reaches the end of its destination, it has a lot of cars -- or water -- piled up. At that point, it crests.

VERIFY CONCLUSION

It can take days for rivers to crest, since the water from tributaries is slowly accumulating and flowing downstream.