The trend is "exceptionally bad news", said University of Miami hurricane researcher Brian McNoldy, since it "smears a landfall out over hundreds of miles of coastline, most notably the storm surge".
"The combination of a unsafe storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline", according to the National Hurricane Center.
Then, it will probably hover along the coast on Saturday, pushing up to 13ft of storm surge and dumping 20 to 30 inches of rain on both states, before heading over the Appalachian Mountains.
The storm was a risky Category 4 hurricane Wednesday but has been downgraded to a Category 2 storm Thursday.
McMullen says high-pressure systems to the west and north are keeping Florence from picking up speed and moving off to the west quickly once it hits land.
Forecasters anxious the storm's damage will be all the worse if it lingers on the coast.
"Just because the wind speeds came down, the intensity of this storm came down to a Category 2, please do not let your guard down", said FEMA Administrator Brock Long. The storm was moving northwest at 10 miles per hour.
The hurricane center is forecasting the storm to hover near the coast Saturday with winds of around 80 miles per hour before landfall, but with rainfall in the 20 to 30 inches range and up to 13 feet of storm surge.
Large and risky, Hurricane Florence is drawing closer to the coast of the Carolinas, where it threatens to become the most intense storm to strike the region in at least 25 years, since Hugo. Tropical Storm Isaac is forecast to approach the Lesser Antilles Islands on Thursday. All that said, a saturated ground, even with tropical storm-force winds, will uproot trees.
Torrential rains are not the only thing Hurricane Florence will bring once it hits landfall. "We're still going to have a Category 4 storm surge", CNN meteorologist Chad Myers said.
"Little change in strength is expected before the center reaches the coast, with weakening expected after the center moves inland", the briefing said.
Florence's weakening as it neared the coast created tension between some who left home and authorities who anxious that the storm could still be deadly. "Near-total power loss is expected with outages that could last from several days to weeks".
The graph below also shows air pressure dropping like insane, an indicator that more powerful parts of the hurricane are coming ashore.
"Your time is running out", he said.
As of 11am local time, the storm was centred 485 miles south east of Wilmington, North Carolina, moving at 15mph.
The National Hurricane Center warned the threat of tornadoes was increasing as Florence neared shore and South Carolina Governor Henry McMaster said the heavy rains could trigger landslides in the western part of his state.
"This is a life-threatening situation".
"Extremely risky winds will cause extensive damage: Well-constructed frame homes could sustain major roof and siding damage".
"The trio of storms is visible in this image acquired by the #SuomiNPP satellite".
"Either no (hotel) rooms are available, or we are denied because the breed or size of dogs", she said.
Numerous communities throughout the region have issued either mandatory or voluntary evacuation orders.
"The shelters are not taking dogs", Ramirez said.