Florence's nighttime winds were down to 115 miles per hour (185 kph) from a high of 140 miles per hour (225 kph), and the Category 4 storm fell to a Category 3, with a further slow weakening expected as the storm nears the coast.
Landfall is expected late Thursday or early Friday, and the National Hurricane Center fears the storm "will slow considerably or stall, leading to a prolonged and exceptionally heavy and risky rainfall event Friday-Sunday".
Hurricanes are massive storm systems that form over warm ocean waters and move toward land.
The News & Observer reports that the storm's path shifted early Wednesday and it is now bearing down on southern North Carolina and northern SC, where it could dump up to 40 inches of rain in places.
Florence's secondary threat to the Carolinas will come from heavy rains, which will fall continuously over a wide area for several days. Then it is likely to hover along the coast Saturday, pushing up to 13 feet (nearly 4 meters) of storm surge and unloading water on both states. The center said the waves were measured by satellite.
A hurricane warning along with a storm surge warning has been issued for Wilmington and surrounding areas. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area.
"The National Hurricane Center forecasts additional strengthening for Florence before it reaches the coastline of North Carolina and SC early Friday, Sept. 14", NASA wrote in the description of the video. Evacuations have been ordered for coastal residents, and the slow-moving storm could dump feet of rain in some places as it slogs through.
"I rode out Hugo", Miller said of a 1989 hurricane that caused widespread damage.
It's unclear exactly how many people fled, but more than 1.7 million people in the Carolinas and Virginia were warned to clear out.
Forecasters anxious the storm's damage will be all the worse if it lingers on the coast.
"We hope to have something left when we get home", she said.
Greg Postel, hurricane and storm specialist for The Weather Channel.
With South Carolina's beach towns more in the bull's-eye because of the shifting forecast, OH vacationers Chris and Nicole Roland put off their departure from North Myrtle Beach to get the maximum amount of time on the sand.