PTC 8 hits the Carolinas while Gordon stays far out to sea » Yale Climate Connections
Even as Potential Tropical Cyclone 8 struggled to make a name for itself off the southeastern U.S. coast on Monday, it brought tropical storm-like weather to the North Carolina coast. Satellite imagery and reconnaissance flights showed PTC 8 was entangled in a stubborn front that extended the circulation and prevented it from developing into a distinct, symmetrical low-pressure system.
At 11 a.m. EDT, PTC 8’s elongated, ill-defined center was located nearly 100 miles east of Charleston, South Carolina, and moving north-northwest at 5 mph. Nearly all of PTC 8’s heavier showers and thunderstorm (convection) activity was concentrated well north of the center over and near the coast of eastern North Carolina and in a separate area well offshore. Highest sustained winds were 50 mph, more than strong enough to make PTC 8 a tropical or subtropical storm. However, because PTC 8 was structured more like a frontal or coastal storm than a non-frontal cyclone, the National Hurricane Center had not yet given it a name. The probability increased that PTC 8 would make landfall in South Carolina Monday evening without ever becoming Tropical or Subtropical Storm Helene.
Regardless of PTC 8’s status, Carolina residents felt its presence Monday, especially on the northern side of the system, toward the southern coast of North Carolina from Wilmington to Cape Fear. A small low pressure system and an intense band of thunderstorms moved inland near Wilmington around noon, with wind gusts of 45 mph reported there at 8:52 a.m. EDT.
https://twitter.com/NWSWilmingtonNC/status/1835703106681909384
As PTC 8 struggles ashore and weakens, the heaviest rains and strongest winds will move across this area through the early hours of Tuesday, possibly reaching totals of 6 to 8 inches in some areas. Locally, amounts could be even higher, as evidenced by a cluster of totals well over 10 inches recorded by weather stations on Bald Head Island, which juts into the Atlantic south of Wilmington.
As of noon EDT Monday, the North Carolina Climate Service’s Bald Head Island Club mesonet station had measured 15.03 inches over the previous 24 hours. Further inland, the highest two-day rainfall totals recorded by the CoCoRaHS volunteer observing network as of Monday morning were 3.61 inches near Morehead City, North Carolina, and 3.5 inches northeast of Wilmington. The torrential rains combined with the storm surge (see below) have caused flooding over three feet in Carolina Beach, North Carolina.
Due to near-normal water levels in eastern North Carolina, widespread inland flooding is not expected as a result of PTC 8. However, flash flooding is possible during localized rainfall.
The storm surge from PTC 8 moved across the coast on Sunday and Monday. Moderate flooding was reported in Charleston Harbor at high tide Sunday afternoon, and minor flooding occurred or was forecast along the coast from Myrtle Beach, South Carolina, to Beaufort, North Carolina, for Monday afternoon and evening. The highest storm surge could cause flooding of one to three feet in a storm surge warning area extending from the South Santee River, South Carolina, to Oregon Inlet, North Carolina, including well inland along the Pamlico, Pungo, Neuse and Bay rivers in southeastern North Carolina.
Light to moderate flooding is possible further north along the Mid-Atlantic coast over the next few days as PTC 8 moves inland and persistent onshore currents produce astronomical high tides.
Gordon remains unbearable as a tropical depression; little else in the Atlantic this week?
Tropical Depression Gordon, downgraded from minimal tropical storm status on Sunday, is barely holding onto the remote eastern tropical Atlantic. As of 11 a.m. EDT Monday, an erratic zone of convection was still concentrated east of Gordon’s low-level center, which was partially exposed at times. Peak sustained winds were 35 mph, and Gordon was located nearly 1,000 miles east of the Leeward Islands, moving west at 7 mph. An approaching upper-level trough will pull Gordon northward by midweek, and it could regain tropical storm strength, but Gordon poses no threat to land areas.
According to the National Hurricane Center’s Tropical Weather Outlook released at 2 p.m. Monday, no new threatening systems are likely to form in the Atlantic over the next seven days. On average over the past few decades (1991-2020), the seventh, eighth and ninth named storms have developed by Sept. 22, so if we go without the eighth storm until next Sunday (assuming PTC 8 doesn’t become Helene), the Atlantic would be well behind the usual climatological pace. As of Sunday, Sept. 15, real-time statistics from Colorado State University showed that the 2024 season also lagged the 1991-2020 pace in hurricane days (13.25 versus the average of 15.2) and accumulated cyclone energy (61 versus the average of 71.9). This week’s activity will not be enough to prevent the 2024 season from falling even further behind at these levels – certainly a welcome development for coastal residents, but also a remarkable and puzzling one given several forecasts predicting a hyperactive Atlantic season for 2024.
Beyond this week, the GFS and European ensemble models predict that a system could develop in the western Caribbean and move northward into the Gulf of Mexico over the next week, but it is too early to predict details with any certainty.
Jeff Masters contributed to this article.
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