Nation

Dave Epstein

Florence is moving at a glacial pace, and that’s bad news for the Carolinas

Florence as seen from space early Wednesday morning. (CIMSS)

Hurricane Florence looks like it’s going to take a very slow path and dump tremendous rain across the Southeast, in addition to coastal flooding and strong winds.

The storm will move at a glacial pace as it approaches the coast. The silver lining is that the winds won’t be as strong as they would be if the storm just barreled toward the coastline. A fast-moving storm would dump a lot of rain, but not to the extent that a slow-moving storm would. The weakening of the winds doesn’t mean this isn’t going to be a bad storm, though.

NOAA/National Weather Service

Winds along the Carolina coast will reach tropical-storm-force (39 miles per hour) early Thursday morning. Hurricane-force winds won’t reach land for at least another 24 hours. Hours upon hours of strong winds and heavy rain will weaken tree roots and make it easier for complete uprooting. That could lead to downed trees, power outages, and other damage.

A timetable of tropical storm-force winds arriving across the southeast.
NOAA/National Weather Service
A timetable of tropical storm-force winds arriving across the southeast.

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The storm puts a cap on what’s been a very wet spring and summer for the Southeast.

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The image below shows the expected upcoming rainfall (left) compared with the percent of normal rainfall the past two months (right). Some areas have received two to three times the normal amount of rain, meaning that the ground is already soaked. When you add in an additional 1 to 2 feet of rain, as Florence could potentially bring, you can see why the possibility of freshwater flooding is a concern.

A side-by-side look at predicted rainfall from Florence and how much above or below rain has been the past two months.
Dave Epstein/NOAA data
A side-by-side look at predicted rainfall from Florence and how much above or below rain has been the past two months.

Storm surge

As Florence moves toward land, it will push a wall of water with it. This water will move farther inland through the little tributaries and inlets shown on the map below. The funneling effect will cause the water to rise higher, and there are predictions of a 6- to 10-foot wall of water in those areas. Any structures that are in the path of this surge will be damaged, if not completely destroyed.

The storm surge from Florence will be worse just to the east of the eye.
Coastal Risk Assessment
The storm surge from Florence will be at its worst just to the east of the eye.

Florence’s slow movement is because of the flow in the upper levels of the atmosphere. This flow is weak and lets the storm move southwest after nearing the coast. There can still be changes to the track of the storm; some areas will fare better than predicted and other regions may fare worse.

The steering currents around Florence are weak and diverge in different directions.
CIMSS
The steering currents around Florence are weak and diverge in different directions.

The worst parts of the storm won’t make it up here to New England, though. Beach weather is in the forecast. If you are taking advantage of this late summer treat, remember that rip currents and large swells will make it to our southern coastline. Be cautious.

Follow Dave Epstein on Twitter @growingwisdom.