9/12/18 5 a.m. update: Florence is a Category 2 storm with winds of 110 miles per hour.
The hurricane is now moving north at around 20km/h, and was expected to slow down today, becoming a tropical storm.
Tropical-storm-force winds extend outward up to 105 miles (165 km) from the center.
According to the NHC 11 p.m. Tuesday update, Tropical Storm Isaac's center is "outrunning" the deep convection by about a degree due to strengthening westerly shear.
No coastal watches or warnings were in effect as of Monday morning.
Although Helene is now a hurricane, it will weaken and be downgraded to a tropical storm by the time it reaches the Azores.
Florence is unlike Hurricane Hugo, a category 4 storm that struck Charleston in 1989.
Gradual weakening is forecast during the next 48 hours, but Olivia is expected to remain a tropical storm as it moves over the main Hawaiian Islands.
Gas explosions set homes north of Boston on fire
At least 10 other people were injured as explosions and fires affected almost 40 homes and businesses in the state, CNN reported . The utility said it was "working with the appropriate authorities to investigate this incident in order to understand its cause".
Met Éireann said: "Current indications are that (ex-) tropical storm Helene will approach Ireland's south coast during Tuesday". This rainfall may cause life-threatening flash flooding.
As for the great storm that hit Britain in 1987, the one BBC weatherman Michael Fish told viewers the night before that there wouldn't be, that wasn't strictly a hurricane.
The storm would be expected to die out by Wednesday, Ms Smith said.
Fox News reported that sustained winds were picking up a bit along the North Carolina coast. Maximum sustained winds are near 35 miles per hour (55 km/h) with higher gusts.
With predicted rainfall measured in feet not inches, forecasters say people living along creeks and rivers in the Carolinas should move to higher ground well ahead of the storm's arrival.
Tropical storm warnings were issued for Martinique, Dominica, and Guadeloupe. This general motion, accompanied by a further decrease in forward speed, is expected to continue through today.
In South Carolina and other parts of North Carolina, rain could be 6 to 12 inches, isolated up to 24 inches. "However, upper-level winds are forecast to become a little more conducive for development, and a tropical depression could still form Thursday or Friday before the system reaches the western Gulf Coast".