’Catastrophic’ Hurricane Dorian blasting Bahamas and bearing down on Florida, Georgia, and the Carolinas

0 0
Read Time8 Minute, 24 Second

Satellite view of Hurricane Dorian Monday morning. (NOAA)
September 2 at 9:03 AM

Category 5 Hurricane Dorian parked itself over the northwestern Bahamas on Sunday night and Monday morning, unleashing a devastating storm surge, destructive winds, and blinding rain. Perched perilously close to the Florida peninsula, Monday is the critical day that will likely determine whether the state is dealt a powerful blow or a less intense scrape.

Just tens of miles and subtle storm wobbles could make the difference between the two scenarios.

The storm has come to a standstill over Grand Bahama Island. If it soon starts to turn north, it would spare Florida from Dorian’s full fury. But if Dorian lumbers just a little more to the west, more serious storm effects would pummel parts of the coastline.

“Only a slight deviation to the left of the official forecast would bring the core of Dorian near or over the Florida east coast,” the National Hurricane Center wrote.

Hurricane and storm surge warnings are in effect for large areas along Florida’s east coast. Storm surge refers to the storm-driven rise in ocean water above normally dry land.

“Although it remains uncertain just how close the eye of Dorian will get to the Florida east coast, the threat of damaging winds and life-threatening storm surge remains high,” the National Weather Service office in Melbourne wrote. “There will be considerable impacts and damage to coastal areas, with at least some effects felt inland as well!”

Serious storm effects are likely in coastal Georgia and the Carolinas in the middle and latter half of the week as Dorian picks up speed and heads north, but here too, to risks are also heavily dependent on the details of the storm track.

A hurricane landfall in the Carolinas, especially North Carolina, is a distinct possibility by late Thursday.

The latest on Hurricane Dorian

As of 8 a.m. Monday, the storm was 35 miles east-northeast of Freeport on Grand Bahama Island and drifting west at just 1 mph. The storm’s peak winds were 165 mph, making it a solid Category 5 storm. Dorian has maintained Category 4 and now Category 5 intensity since Saturday, an unusually long period.

Hurricane-force winds extend outward up to 45 miles from the center and tropical-storm-force winds extend outward up to 140 miles. The latest forecast from the Hurricane Center calls for Dorian to remain a Category 5 storm until Monday night before slowly weakening, but still remaining a formidable hurricane, as it makes its closest pass to Florida (at between Category 3 and 4 strength) and northward to the Carolinas (around a Category 2).

“It is anticipated that the system will remain a dangerous major hurricane for the next several days,” the Hurricane Center wrote.

Northwest Bahamas took a nightmarish extended direct hit

While Florida and areas farther north await effects from the monster storm, a “catastrophic” scenario has unfolded in the northwestern Bahamas, where the storm’s eyewall, the ring of destructive winds around the center, struck Sunday and has since lingered. Three islands endured direct hits Sunday: Cay, Great Abaco, and Grand Bahama Island.

On both Great Abaco and Grand Bahama Island, the Hurricane Center described a “life-threatening situation” Sunday which is continuing on Monday.

The eyewall still hovered over Grand Bahama Island Monday morning where the storm was predicted to unleash wind gusts to nearly 200 mph, along with storm surge flooding of 18 to 23 feet above normal tide levels.

The extended nature of the direct hit has meant that these areas have been subjected to extreme winds and storm surge flooding during multiple high tides, tearing infrastructure apart and subjecting anyone who did not evacuate before the storm to a truly terrifying ordeal.

“These hazards will continue over Grand Bahama Island during most of the day, causing extreme destruction on the island,” the Hurricane Center wrote.

Pounding rain (up to 30 inches), destructive winds and the storm surge may not substantially ease until the second half of Tuesday.

This is a storm that could reshape the northwest Bahamas, particularly Great Abaco and Grand Bahama, for decades.

Complicated forecast for Florida

The hurricane warnings posted in Florida are focused on the period from Monday night through early Wednesday. Tropical storm-force winds could begin in south Florida as soon as Monday evening and on Tuesday farther north. These winds are likely to continue into Wednesday, perhaps reaching hurricane-force late Tuesday or Wednesday depending on how close to the coast Dorian tracks.

Some computer models show the center of Dorian coming closest to the northern half of Florida’s east coast Tuesday night into Wednesday, when conditions may become most hazardous.

The latest storm surge forecast for Florida shows that if the peak surge occurs at the time of high tide, the area from Lantana (just south of West Palm Beach) to the mouth of the St. Mary’s River (north of Amelia Island) could see 4 to 7 feet of water above ground, while the region from Deerfield Beach to Lantana experiences 2 to 4 feet.

“The threat for life-threatening storm surge also remains high, and severe erosion of the beaches and dune lines is a near certainty! The combination of surge and high astronomical tides will cause severe runup of waves and water, resulting in inundation of many coastal locations,” the Weather Service office in Melbourne wrote.

On top of that, about two to four inches of rain is projected to fall.

Because the storm is predicted to be a slow mover, effects from wind, rain and storm surge could be prolonged, lingering through the middle of next week.

The forecast is highly sensitive to the storm track and subtle shifts to the east or west would result in less or more severe wind, surge, and rain..

Forecast for coastal Georgia and the Carolinas

By Tuesday, conditions are expected to deteriorate in coastal Georgia, by Wednesday in South Carolina, and by Thursday in North Carolina. But just how much is uncertain. Where and whether Dorian makes landfall will depend on the exact trajectory of its turn relative to the coast as it turns north and then starts to bend northeastward.

Scenarios involving a direct hit, a scrape and a graze are possible based on available forecasts. The likelihood of a direct hit is perhaps most likely in North Carolina because its coast sticks out into the ocean farthest east.

“There is an increasing likelihood of strong winds and dangerous storm surge along the coasts of Georgia, South Carolina, and North Carolina later this week,” the Hurricane Center wrote. “Residents in these areas should continue to monitor the progress of Dorian and listen to advice given by local emergency officials.”

Locations even farther north from Virginia Beach to the Delmarva and even up to Cape Cod could get brushed by the storm Friday and Saturday.

Model forecasts

The overwhelming majority of computer model forecasts keep the center of Dorian just to the east of the Florida coast rather than bringing the eye of the storm ashore.

However, there are still some outliers which bring the eye onshore or right to the coastline, particularly in the northern half of the state.

Group of simulations from American (blue) and European (red) computer models from Monday morning for Hurricane Dorian. Each color strand represents a different model simulation with slightly altered input data. Note that the strands are clustered together where the forecast track is most confident but diverge where the course of the storm is less certain. The bold red line is the average of all of the European model simulations, while the bold blue one is the average of all the American model simulations. (StormVistaWxModels.com)

Farther north, from Georgia to the Carolinas, the margin between a landfall and offshore track is also razor thin. However, of all the locations between Florida and the Mid-Atlantic coast, models suggest the North Carolina coast between Wilmington and the Outer Banks may be most prone to a hurricane landfall on Thursday.

Dorian’s place in history

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.

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 in four straight years, according to Capital Weather Gang’s 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.

Andrew Freedman contributed to this story.