Florence expected to stall over Carolinas, bring widespread flooding

With 110 mph winds, hurricane weakens slightly to become Category 2 storm

By Bryan Norcross - Hurricane Specialist

PEMBROKE PARK, Fla. - Hurricane Florence is on course for the North and South Carolina coast. When it gets there, it is forecast to stall. It appears that the bizarre scenario of a meandering hurricane that will prolong the misery is now likely. The new forecast indicates that much of South Carolina and perhaps part of Georgia will eventually be impacted by the storm as well.

There are three systems of concern:

  • Hurricane Florence is on track to be an historic disaster in the Carolinas extending at least through the weekend.
  • Tropical Storm Isaac has significantly weakened.  Still, it will move through the eastern Caribbean islands Thursday, likely as a tropical storm. There are question marks about its long-term future. It will have to be watched.
  • Disturbance 95L -- using the National Weather Service numbering system -- is somewhat less organized Wednesday. It may still develop into an organized system in the western Gulf and threaten Texas.

Hurricane Florence now has top winds estimated at 110 mph -- Category 2. While the highest winds have come down a bit, the energy is spread out in a larger storm, which will increase the storm surge over more of the coast.  

The track through Thursday is unchanged. The weather will deteriorate on the North Carolina coast Thursday, and the eye is expected to impact the coast on Friday. At that point the storm is expected to have slowed to a crawl, and to move south along or just offshore of the South Carolina coastline.

If the center stays over the water, the hurricane will stay stronger longer, prolonging the hammering on the coastline.

Hurricane warnings and storm surge warnings are in effect for most of the South Carolina and all of the North Carolina coast.  Storm surge will be life-threatening over the part of that coastline that ends up north of the storm center. The National Hurricane Center is forecasting the ocean water to be pushed 9 to 13 feet over the land on the Outer Banks of North Carolina, with lesser but still life-threatening surge over most of the Carolina coast and up into the various bays, rivers and inlets.

In addition, the rainfall forecast has now increased to 20 to 30 inches for the coastal areas of the Carolinas, with some spots receiving 40 inches. Inland areas will receive less, but still 5 to 10 inches with some areas receiving 20 inches of rain. All that water will try to run out the rivers, streams and inlets while the storm surge is pushing in from the ocean. It is a recipe for a disastrous flood, on top of the damage from the wind.

A hurricane that stalls and meanders is one of the most destructive scenarios.

Here are the key messages from the National Hurricane Center concerning Hurricane Florence:

  • A life-threatening storm surge is now highly likely along portions of the coastlines of South Carolina and North Carolina, and a storm surge warning is in effect for a portion of this area. All interests in these areas should complete preparations and follow any advice given by local officials.
  • Life-threatening, catastrophic flash flooding and prolonged significant river flooding are likely over portions of the Carolinas and the southern and central Appalachians late this week into early next week, as Florence is expected to slow down as it approaches the coast and moves inland.
  • Damaging hurricane-force winds are likely along portions of the coasts of South Carolina and North Carolina, and a hurricane warning is in effect. Strong winds could also spread inland into portions of the Carolinas.
  • Large swells affecting Bermuda, portions of the U.S. East Coast, and the northwestern and central Bahamas will continue this week, resulting in life-threatening surf and rip currents.

Tropical Storm Isaac is struggling with hostile upper-level winds, which are keeping it from strengthening.  The peak winds are still estimated at 60 mph. The official forecast keeps it below hurricane strength as it passes through the eastern Caribbean islands Thursday.

The threat of some strong winds and heavy rainfall still exists for the affected islands, especially Martinique, Dominica and Guadeloupe.

Some heavy rain is also possible in Puerto Rico and the southern Virgin Islands.

Isaac is forecast to move into the central Caribbean Sea over the weekend and weaken. The eventual track of what's left of Isaac may have something to do with the way Florence tracks and how strong it remains, which is, of course, doubly uncertain. So we'll have to watch it. The remnants of Isaac could get pulled north toward Cuba or the Gulf six or seven days from now.

Here are key messages from the National Hurricane Center concerning Isaac:
  • Isaac is expected to remain at tropical storm intensity when it moves across the Lesser Antilles on Thursday, and tropical storm warnings are in effect for Martinique, Dominica and Guadeloupe. Tropical storm watches are in effect for Montserrat, St. Kitts and Nevis, Antigua and Saba and St. Eustatius. Interests on those islands should follow any advice given by their local officials.
  • Life-threatening flash flooding is possible with Isaac. The storm is expected to produce total rainfall accumulations of 2 to 4 inches, with isolated amounts up to 8 inches, across Martinique, Dominica and Guadeloupe. Rainfall amounts of 1 to 2 inches with isolated amounts to 4 inches are expected across Puerto Rico and the southern U.S. Virgin Islands.

Disturbance 95L was showing signs of organization, but less so Wednesday. It will move across the Yucatan Peninsula of Mexico and into the southern and western Gulf, where it might organize into a tropical depression or tropical storm over the next couple of days. These systems can spin up quickly, so residents in northern Mexico and Texas should stay informed.

Hurricane Helene, newly named Subtropical Storm Joyce and the potential disturbance are not expected to affect land over the next several days, if ever.

Tropical Storm Olivia is approaching the Hawaiian Islands.  The biggest threat is from heavy rain over the mountainous islands.

Copyright 2018 by WPLG Local10.com - All rights reserved.