Some fluctuation in wind speeds are expected, and weakening forecast Thursday, but it's still expected to be a fierce storm triggering risky flooding.
"These enormous waves are produced by being trapped along with very strong winds moving in the same direction (as) the storm's motion", explained a tweet sent by the analysis branch.
Duke Energy says damage from Hurricane Florence could cut off electricity to three-quarters of its 4 million customers in the Carolinas, and the outages could last for weeks.
Maximum sustained winds remain near 68 miles per hour with higher gusts.
Tropical storm watches were in effect Tuesday for Antigua, Montserrat and St. Kitts and Nevis.
A considerable portion of east coast residents are preparing for or evacuating from the category 2 hurricane to make landfall.
"Mild, very humid conditions are expected to develop during Monday, with rain moving up from the south in freshening southerly winds".
"According to the IPMA's forecast, it is likely that the western islands [Flores and Corvo] should begin to feel the effects of the storm from Saturday afternoon". This rainfall may cause risky flash flooding.
CNN meteorologist Taylor Ward said the main threat will be flooding, with predictions of 5 to 10 inches, with isolated totals of 15 inches.
NASA video shows Hurricane Florence from space as it makes landfall
Roy Cooper said Friday that Florence is "wreaking havoc" and he's concerned "whole communities" could be wiped away. Myrtle Beach, a SC beach resort, was deserted with empty streets, boarded up storefronts and very little traffic.
Met Office meteorologist Alex Deakin said: "It's an intense area of low pressure heading up towards the United Kingdom bringing some tropical air with it".
Isaac became the fifth hurricane of the season late Sunday and was initially expected to strengthen, potentially becoming a Cat 2 storm with 100 miles per hour winds, as it crossed warm ocean waters.
While Hurricane Florence continues barreling toward the Carolina coast, the Caribbean got some good news Wednesday: Isaac appears to be weakening.
"Stay tuned" was the National Hurricane Center's best advice Friday night.
Sen. Jeff Merkley of OR said the administration was taking money from FEMA's "response and recovery" to the Immigration and Customs Enforcement agency at a time when Hurricane Florence is bearing down on the Southeast U.S. coast. These swells are likely to cause life-threatening surf and rip current conditions.
News 6's Erik Sandoval was live in Wilmington shortly before the storm made landfall.
The water could reach as high as 9 to 13 feet "from Cape Fear to Cape Lookout, including the Neuse, Pamlico, Pungo and Bay Rivers".
Current estimates have Isaac passing nearly 150 miles south of St. Croix early Friday morning.