A man walks a flooded street in Old Town Alexandria, Virginia.
These alerts are usually issued about 48 hours before storms are set to touch down, when the arrival of tropical force winds would make any last-minute preparation hard. Although North Carolina is still expected to see the worst of the storm, a more southern track would mean that states further north - like Virginia - could be spared of some nasty weather. "It's big and it's vicious".
The NHC warned they're likely to cause "life-threatening surf and rip current conditions".
The center of the massive storm is forecast to make landfall along a stretch of coastline already saturated by rising seas and then meander Thursday, Friday and Saturday, inundating several states and triggering life-threatening floods.
Some 3,000 people died in the aftermath of that storm.
US President Donald Trump signed declarations of emergency on Tuesday for both North Carolina and SC, freeing up federal money and resources for storm response.
Mr Cooper and his counterparts in neighbouring SC and Virginia ordered about one million people to evacuate coastal homes, including along the Outer Banks barrier islands.
South Carolina Governor Henry McMaster on Monday ordered the mandatory evacuation of one million coastal residents.
The latest GFS Model shows the storm approaching North Carolina, covering the state in precipitation over a fairly short amount of time. "The threat will be inland, so I'm afraid, based on my experience at FEMA, that the public probably not as prepared as everybody would like", said Craig Fugate, former director of the Federal Emergency Management Agency.
The office of Virginia Governor Ralph Northam predicted "catastrophic inland flooding, high winds and possible widespread power outages".
Rainfall could be up to 20in (50cm) in some areas.
On the opposite side of the country, officials in Hawaii are warning residents and tourists to brace for the arrival of Tropical Storm Olivia.
Forecasters say Olivia - with current wind speeds of 65 miles per hour - will make landfall on Wednesday morning. The Air Force, which operates F-22 Raptors and other jets from Joint Base Langley-Eustis near Hampton, Va., began sending planes to Rickenbacker Air National Guard Base in OH on Tuesday.