The National Hurricane Center forecasts hurricane storm-force winds, heavy bands of rain and a storm surge along the South Carolina coast from Hurricane Dorian through Friday morning.
Here is what you need to know about the storm:
What can South Carolina expect?
The biggest threats are hurricane and tropical storm-force winds, heavy rainfall, possible isolated tornadoes, coastal flooding and dangerous surf conditions, according to the National Weather Service. Rainfall forecasts vary. A storm surge above 3 feet is predicted in some locations along South Carolina's coast.
What is storm surge?
Surge is the height of the ocean above regular tide. Wind from a major hurricane pushes a tremendous amount of ocean water toward the coast on the northeast side of the storm's eye. This is where the wind blows perpendicular to the coastline. On the other side of the storm, the wind will be blowing back out to sea, creating less surge. During Hurricane Hugo in 1989, it was measured at 16 feet in McClellanville. Six feet of saltwater rushed into a high school gym, where residents were sheltering. This is why it's important for everyone on the immediate coast to leave before such a system makes landfall there.
Why is the speed of the storm a factor?
As of Wednesday morning, Dorian was traveling at 8 mph. Slow-moving hurricanes are problematic because the more they linger in an area, the longer rain and winds persist. That’s what happened with Hurricane Florence, which traveled at 5 mph as it approached the Carolinas and dumped rain for several days, and Hurricane Harvey, which hung around Houston for four days and moved at 3 mph.
Have warnings been issued?
Hurricane and storm surge warnings have been issued for the entire length of South Carolina's 187-mile coastline. Gov. Henry McMaster announced evacuation orders on Sunday for all or portions of Charleston, Berkeley, Dorchester, Beaufort, Colleton, Jasper, Georgetown and Horry.
What does an evacuation order mean?
It means the state wants you to get out if you live in a coastal zone for which an evacuation is ordered. It doesn't mean the authorities will show up at your home and take you away if you refuse to leave. They can't do that. But if you chose to stay and the storm is bad, it might take time for first responders to reach you if you have an emergency. They might not be able to reach you at all. Prepare to fend for yourself.
What bridges are off limits?
If sustained wind speeds reach 30 mph, residents driving high-profile vehicles like tractor-trailers and box-type trucks are advised not to use the bridges. If wind speeds reach 40 mph, the bridges will be deemed unsafe for all travel. They are not physically closed. But the S.C. Department of Emergency Management warned drivers against using specific bridges beginning Wednesday afternoon. That list includes the following:
- McTeer Bridge (U.S. 21A) in Beaufort County
- Don Holt Bridge over the Cooper River (I-526) in Berkeley County
- Stono River Bridge (S.C. 700) in Charleston County
- Arthur Ravenel Jr. Bridge & Ramps (U.S. 17) in Charleston County
- Wando River Bridge (I-526) in Charleston County
- Wando Bridge (S.C. 41) in Charleston County
- Isle of Palms connector (S.C. 517) in Charleston County
- Bridge over the Sam Pit River (U.S. 17) in Georgetown County
- Bridge over the Intracoastal Waterway at Socastee (U.S. 17) in Horry County
- Little River Bridge (U.S. 17) in Horry County
- Pee Dee River Bridge (U.S. 701) in Horry County
How do I report a power outage?
You should report power outages to whichever utility you pay your electric bill to. In South Carolina, that will either be Santee Cooper, one of the 20 electric cooperatives in the state, Dominion Energy (formerly S.C. Electric & Gas) or Duke Energy (both Duke Energy Carolinas and Duke Energy Progress).
Here's where you can report those outages:
- Santee Cooper customers can call 1-888-769-7688.
- Co-op customers can find the correct number to call at http://www.ecsc.org/content/reporting-your-power-outage
- Dominion Energy customers can call 1-888-333-4465.
- Duke Energy customers can call 1-800-419-6356.
Where should I get information?
In addition to the National Hurricane Center, city, county and state emergency government emergency officials are reliable sources for information. The state also has a hotline: 803-737-8500. Local media outlets also relay storm-related information.
Which forecast is most reliable?
The Weather Service official forecast is the best for predicting storms traveling through the Atlantic Ocean. This forecast features the “cone of uncertainty” and outperforms individual computer models run by organizations across the globe. This is because the forecast uses those models, like the European model run by the European Centre for Medium-range Weather Forecasts, as tools to come up with their forecasts.
What's the "cone of uncertainty"?
It's a colloquial term for the possible track of a tropical cyclone's eye over the next five days, and it's plotted by the National Hurricane Center in Miami. Meteorologists consult computer models, observations from "hurricane hunter" airplanes and their own expertise in coming up with a cone. The cone's width is based on a historical margin of error. Forecasts have become more exact in recent years. Based on data from the past five seasons, a storm's actual path can be expected to stay within the cone 60 percent to 70 percent of the time, the Hurricane Center said. Still, cyclones can defy computers and take on a mind of their own.
If I'm out of the cone, am I in the clear?
No. The cone is the potential path of the eye. Damaging wind, torrential rain and conditions ripe for rapid tornado formation can extend hundreds of miles from the center in large storms. Dorian is expected to bring hurricane-force winds (at least 74 mph or above) to the coast. And those winds currently extend 60 miles from the eye of the storm.