Florence's storm surge will probably be 7 to 11 feet (more than 2 to 3 meters) above ground in parts of North Carolina, according to the National Hurricane Center.
North Carolina Gov. Roy Cooper warned: "Don't relax, don't get complacent".
The bulk of the three media briefings held by police chief Dan House surrounded how they were still anticipating the serious and catastrophic storm surge as well as hurricane force winds. The height of the water that we will see on the coast is the amount of storm surge plus the tide and any additional rain water.
The North Carolina coast has already started to feel tropical force winds today.
Emergency Management services in North Carolina are reporting that 497,255 customers are without power in North Carolina as Hurricane Florence makes landfall.
"I'm not going to put our personnel in harm's way", said Dan House. "I've got four cats inside the house".
"But we can't replace us so we made a decision to come here".
After reaching a terrifying Category 4 peak of 140 mph (225 kph) earlier in the week, Florence made landfall as a Category 1 hurricane at 7:15 a.m.at Wrightsville Beach, a few miles (kilometers) east of Wilmington and not far from the SC line.
By late Thursday afternoon, Florence's fierce headwinds were already uprooting trees and tearing down power lines and had ripped the roof off of at least one building in coastal North Carolina, according to news station WGHP.
Florence's top winds were clocked on Thursday evening at 90 miles per hour (150 km/h) as it churned in the Atlantic Ocean, down from a peak of 140 miles per hour (224 km/h) earlier this week when it was classified a Category 4 storm. Forecasters are predicting as much as 40in of rain in some localized areas. Rainfalls up to 40 inches (102 centimeters) in some places are expected in a region ranging from coastal North Carolina to northeastern SC, with flash flooding likely, according to the NHC.
Will Epperson, a 36-year-old golf course assistant superintendent, said he and his wife had planned to ride out the storm at their home in Hampstead, North Carolina, but reconsidered due to its ferocity.
The storm is not expected to change much in strength before making landfall, but states up and down the East Coast have a great potential for severe weather.
"Your time is running out", he warned. "Inland flooding kills a lot of people, unfortunately, and that's what we're about to see", he said.
Almost 2 million coastal residents are now under mandatory evacuation orders, although it remains unclear how many have actually done so.
Officials in several states have declared states of emergency, including in the Carolinas, Georgia, Virginia and Maryland, where coastal areas are still recovering from summer storms.
Utility companies said millions were expected to lose power and restoring it could take weeks.
Roughly 1 million people are under evacuation orders.
Horton pleaded for volunteers to take in their animals for the duration of the storm, a common, plaintive refrain at other shelters across the area.