January 20, 2020
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Dorian’s ‘life-threatening’ storm surge, torrential rains, winds pound Carolinas

Meg Kinnard | AP
Meg Kinnard | AP
Heavy rain and wind move through Charleston, S.C. on Thursday, Sept. 5, 2019. Hurricane Dorian raked the coastal Carolinas with howling, window-rattling winds and sideways rain Thursday, spinning off tornadoes and knocking out power to more than 200,000 homes and businesses as it pushed northward toward the dangerously exposed Outer Banks.

Powerful Hurricane Dorian is unleashing its full array of hazards on the Carolinas just days after causing a humanitarian crisis in the northwestern Bahamas and then zagging around the Florida Peninsula.

The Category 3 storm has already flooded parts of downtown Charleston, South Carolina, with a combination of storm surge and rainfall runoff, prompting a flash-flood warning through midmorning there, in addition to a storm-surge warning.

If it makes landfall in North Carolina, it would be the first Category 3 to do so since Fran in 1996. While intensifying, its wind field has expanded, with tropical-storm and hurricane-force winds covering more territory. Even the Virginia Tidewater and southern Delmarva Peninsula could endure tropical storm conditions by Friday, after which the storm is expected finally to move to the northeast.

Already on Thursday, residents of coastal South and North Carolina were losing power as tropical-storm-force winds ramped up close to 70 mph, with hurricane-force winds expected to overspread coastal South Carolina during the morning. Tropical-storm and hurricane conditions are anticipated for coastal North Carolina late Thursday.

Peak winds reached 90 to 100 mph or higher in gusts, particularly right along the shoreline. In addition, these areas, particularly in North Carolina’s Outer Banks, are expecting up to 15 inches of rain.

The storm is likely to buffet the entire coastline of South Carolina throughout the day and lash North Carolina through the first half of Friday. Its impacts will also be felt northward into coastal Virginia, where low-lying communities such as Hampton Roads could see a storm surge of two to four feet, according to the National Hurricane Center.

The storm was spinning just off the coast of South Carolina as of Thursday morning. It is projected to remain near or cross over the coast of North Carolina, with the most likely landfall point – if there is a landfall – being the Outer Banks.

Hurricane Dorian’s reintensification on Wednesday evening, when it regained “major” hurricane status as a Category 3 storm, combined with its expanded size, means that areas all the way northward to southeastern Virginia will feel the effects of this storm.

As of 8 a.m. ET, Hurricane Dorian was located 70 miles south-southeast of Charleston, S.C., and about 110 miles south-southwest of Wilmington, N.C. The storm was moving north-northeast at 8 mph.

Hurricane Dorian had maximum sustained winds of 115 mph, with higher gusts, making it a Category 3 storm. It is forecast to weaken some on Thursday as it interacts with land and is exposed to wind shear, or winds moving with different speeds or direction with height.

The storm was able to regain some intensity on Wednesday night as it loosened its grip on the Florida coast and traversed warm waters off the southeastern coast of Georgia. What had been looking like a much more ragged hurricane became more symmetrical, with a large, 50-mile-wide eye having replaced the sinister-looking pinhole eye structure it exhibited when it hit the Bahamas.

The storm is expected to remain a powerful hurricane through Friday, before transitioning into more of a nontropical storm system that may go on to batter the Canadian Maritimes. Tropical storm watches have been hoisted as far north as extreme southeastern New England, including Martha’s Vineyard and Nantucket, even though the center of Dorian is expected to stay about 150 miles offshore there.

Hurricane-force winds extend outward up to 60 miles from the center, and tropical-storm-force winds extend outward up to 195 miles. The wind field may expand further on Thursday.

The Carolinas have an intense 24-hour-plus period of tropical storm and hurricane force winds to endure, along with coastal flooding and flash flooding from rainfall that is expected to reach up to 15 inches.

Coastal flooding due to storm surge is a risk from Georgia to southeastern Virginia, where a storm-driven rise in water above normally dry land is predicted to reach at least two to four feet, and up to eight feet in places. Storm surge warnings cover this entire zone.

Hurricane Dorian could cause one of the top five water levels on record in Charleston, with a predicted surge of 9.8 feet (previous forecasts projected 10.3 feet), not counting coastal inundation from heavy rains. Such a surge would be enough to flood large portions of the low-lying city. Of particular concern is the high tide on Thursday afternoon, when winds may still be blowing onshore.

If winds turn offshore by that point, Charleston may see lower water levels.

Coastal southeastern North Carolina will see the worst storm surge conditions during the high tide Thursday afternoon and late Thursday night into early Friday morning.

According to the Weather Service office in Charleston, based on the present forecast track, the result could be particularly severe. Among the possible effects, it listed: “Large areas of deep inundation with storm surge flooding accentuated by battering waves. Structural damage to buildings, with several washing away. Damage compounded by floating debris. Locations may be uninhabitable for an extended period.”

For many historic homes in Charleston, this is the fourth major flood in just the past five years, given other tropical cyclones and astronomical high tides.

According to Sarah Watson, a coastal climate and resilience specialist with the South Carolina Sea Grant Consortium as well as the Carolinas Integrated Sciences and Assessments, water was already coming out of the drains on some Charleston roads as of midday Wednesday. In an interview, she noted that the combination of high astronomical tides plus heavy rains will keep water levels elevated for an extended period.

“One of the things I’m looking at, you know, is people are tired. . . . You’re starting to see that in people’s conversations and faces that they’re weary and tired” from repeated bouts of coastal flooding, Watson said. Unable to elevate their historic structures, many have resorted to implementing their own flood-protection barriers.

A landfall or near-landfall from a strong Category 2 or low-end Category 3 storm is relatively uncommon in the Carolinas, and these storms have grown more damaging in some spots due to the combination of sea level rise and land subsidence that makes communities more vulnerable to even a modest storm surge.

For example, from 1900 to 2018, sea level has risen by 1.26 feet in Charleston, with an annual increase averaging 0.13 inches per year. That may not seem like much, but in a low-lying, highly populated area, every inch of sea-level rise matters.

The strongest winds from Hurricane Dorian are expected to scrape the Outer Banks of North Carolina, with gusts of over 100 mph, depending on the storm’s exact track. Gusts to 100 mph or higher could also occur in Wilmington, according to the Weather Service.

The risk of tornadoes from the storm’s energetic tropical rain bands also exists on Thursday into Friday, particularly in northeastern South Carolina northeastward into North Carolina, where a tornado watch was issued Thursday morning.

Tornadoes associated with tropical storms and hurricanes tend to be weak and short-lived, but they can still be deadly and damaging since they are especially difficult to forecast.

While the storm could bring tropical-storm conditions to the tidal Potomac south of Cobb Island, it is not forecast to send a storm surge riding up the Potomac River toward Washington, D.C.

Locations farther north from Virginia Beach to the southern Delmarva are expected to be scraped by the storm through Friday night, with heavy rains, tropical-storm-force winds and coastal flooding. A tropical storm warning is in effect from the North Carolina-Virginia border to Chincoteague, and for the Chesapeake Bay from Smith Point southward, where three to six inches of rain are possible, along with wind gusts up to 60 mph.

The storm surge in this zone could reach to two to four feet above the normal high tide.

A Tropical Storm Watch has been issued from north of Chincoteague, Virginia, to Fenwick Island, Delaware, for the Chesapeake Bay from Smith Point to Drum Point, and for the tidal Potomac River south of Cobb Island. This area sits along the western edge of where significant wind and rain are possible and may or may not experience tropical-storm conditions.

Dorian is tied for the second-strongest storm (as judged by its maximum sustained winds) ever recorded in the Atlantic Ocean, behind Hurricane Allen of 1980, and, after striking the northern Bahamas, tied with the 1935 Labor Day Hurricane for the title of the strongest Atlantic hurricane at landfall.

It is only the second Category 5 hurricane to make landfall in the Bahamas since 1983, according to Phil Klotzbach of Colorado State University. The only other is Hurricane Andrew in 1992. The international hurricane database goes back continuously only to 1983.

[Hurricane Dorian has smashed all sorts of intensity records in the Atlantic Ocean]

The storm’s peak sustained winds rank as the strongest so far north in the Atlantic Ocean east of Florida on record. Its pressure, which bottomed out at 910 millibars, is significantly lower than Hurricane Andrew’s when it made landfall in South Florida in 1992. (The lower the pressure, the stronger the storm.)

With Dorian attaining Category 5 strength, this is the first time since the start of the satellite era (in the 1960s) that Category 5 storms have developed in the tropical Atlantic for four straight years, according to Capital Weather Gang tropical weather expert Brian McNoldy.

The unusual strength of Dorian and the rate at which it developed is consistent with the expectation of more intense hurricanes in a warming world. Some studies have shown increases in hurricane rapid intensification, and modeling studies project an uptick in the frequency of Category 4 and 5 storms.

Dorian may have also set a record for the longest period of Category 4 and 5 conditions to strike one location in the North Atlantic Basin since the dawn of the satellite era, but historical data is relatively sparse.

Officials in the United States and Bahamas are rushing to kick humanitarian relief efforts into gear on Thursday as the scope of the devastation in the Bahamas becomes clearer.

Between late Sunday and Tuesday, Dorian slammed into the northwestern Bahamas with wind gusts up to 220 mph and a 23-foot storm surge. Video and images emerging from the Bahamas show a toll of absolute devastation on Great Abaco and Grand Bahama Islands, two locations where the eye of the storm made landfall.

Grand Bahama Island suffered an onslaught from this storm that few places on Earth have experienced, remaining in the eyewall of a major hurricane (between Category 3 and 5) for 40 hours. The eyewall is the most severe part of a hurricane that contains its strongest winds and generates the most destructive storm-surge flooding.

Dorian came to a virtual standstill as it encountered the northwest Bahamas. Between 3 a.m. on Labor Day and 5 a.m. on Tuesday, the storm moved just 30 miles in 28 hours. In addition to wind gusts up to 220 mph and a 23-foot storm surge, up to 40 inches of rain were estimated in some areas.


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