Florida’s fate depends on Dorian taking a sharp north turn by Tuesday
September 2 at 11:15 PM
Category 4 Hurricane Dorian has parked itself over the northwestern Bahamas since Sunday night, unleashing a nightmare 24-hour siege of devastating storm surge, destructive winds and blinding rain. With Dorian perched perilously close to the Florida peninsula, Monday night into the first part of Tuesday has become the critical time that is likely to 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, Florida would be spared 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. Such small differences in the track forecast will have similar implications farther north, from coastal Georgia to the Carolinas.
In its 11 p.m. bulletin Monday, the National Hurricane Center wrote Dorian’s track forecast remains “dangerously close to the east coast of the U.S. from Florida to North Carolina during the next 3 days or so.”
For this reason, the National Hurricane Center has issued hurricane, storm surge, and tropical storm watches and warnings from the Atlantic coast of Florida northward into South Carolina. Storm surge refers to the storm-driven rise in ocean water above normally dry land.
“[T]he threat of damaging winds and life-threatening storm surge remains high,” the National Weather Service office in Melbourne, Fla., 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. A hurricane landfall in the Carolinas, especially North Carolina, is a distinct possibility by late Thursday.
The latest on Hurricane Dorian
As of 11 p.m. on Monday, the storm was 30 miles northeast of Freeport on Grand Bahama Island and stalled. The storm’s peak sustained winds were 130 mph, making it a Category 4 storm. Dorian has maintained Category 4 or 5 intensity since Saturday, an unusually long period.
Radar from South Florida showed Dorian’s outermost rain bands pivoting inland producing occasional gusty showers. Late Monday evening Juno Beach pier in northern Palm Beach County clocked a sustained wind of 46 mph (tropical-storm force) and gust to 56 mph and the Weather Service in Miami warned showers coming onshore could produce gusts up to 50 mph or so into the night.
Hurricane-force winds extend outward up to 45 miles from the center and tropical-storm-force winds extend outward up to 150 miles. The latest forecast from the Hurricane Center calls for Dorian to remain a Category 4 storm until Monday night before slowly weakening, but remaining a formidable hurricane, as it makes its closest pass to Florida (around a Category 3) and northward to the Carolinas (around a Category 2).
“Regardless of the details of the intensity forecast, the bottom line is that Dorian is expected to remain a powerful hurricane as it tracks very near the east coast of the U.S. from Florida to North Carolina during the next few days,” the Hurricane Center wrote.
Northwest Bahamas taking 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 then stalled through Monday evening.
In the process, three islands endured direct hits Sunday: Elbow Cay, Great Abaco and Grand Bahama Island. Dorian hardly budged over Grand Bahama Island Sunday night and all of Monday as the Hurricane Center warned of wind gusts between 165 and 220 mph and a storm surge up to 23 feet. At least five people have died.
#Dorian Has wreaked havoc on Abacos and Grand Bahama Islands over the past 24+ hours. Here is a satellite recap as it approached, made a 2nd landfall and then stalled out over Grand Bahama Island. Now the storm is finally starting to pull away. In its wake utter devastation… pic.twitter.com/nyFzaPxQOF
— Cristopher Cace (@CristCacewx) September 2, 2019
The Hurricane Center described a “life-threatening situation” in Great Abaco Sunday and on Grand Bahama Island through Sunday night and Monday. It stated the wind and storm surge hazards would cause “extreme destruction.”
The eyewall finally showed signs of lifting north of Grand Bahama on Monday evening but continued to lash its north coast. It could take until Tuesday morning for the worst of Dorian to finally depart.
The extended nature of the direct hit has meant that these areas have been hit with 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.
Pounding rain (totaling up to 30 inches), damaging winds and the storm surge may not entirely ease until the second half of Tuesday in the region.
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 began Monday afternoon in coastal South Florida and should spread north Tuesday. These winds are likely to continue into Wednesday, perhaps reaching hurricane-force strength 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 Georgia Border could see four to seven feet of water above ground, while the region from Deerfield Beach to Lantana could experience two to four 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 four to eight 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, the Carolinas, and farther north
Conditions are expected to deteriorate by early Wednesday in coastal Georgia, by late 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.
A hurricane watch was issued Monday for coastal Georgia and the South Carolina coast as far north as South Santee Island (which is just south of Myrtle Beach).
“Life-threatening storm surge and dangerous hurricane-force winds are expected along portions of … the coasts of Georgia and South Carolina, regardless of the exact track of Dorian’s center,” the Hurricane Center wrote. “Water levels could begin to rise well in advance of the arrival of strong winds. “
The Hurricane Center projects a storm surge of 4 to 7 feet in coastal Georgia north to the South Santee River in South Carolina.
While specific projections are not yet available farther north, a direct hit is perhaps most likely in North Carolina because its coast sticks out into the ocean farthest east.
“The risk of life-threatening storm surge and hurricane-force winds continues to increase along the coast North Carolina,” the Hurricane Center wrote. “Residents in these areas should follow 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. Virginia governor Ralph Northam (D) declared a state of emergency ahead of the storm.
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 that 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 afternoon 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 that 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 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.