North Carolina Outer Banks bracing for flooding, wind as Hurricane Erin passes by offshore

The North Carolina Outer Banks and other beaches along the Atlantic coast of the United States will bear the brunt of Erin as the major hurricane grows in size and its winds and waves extend well beyond the eye of the storm, AccuWeather meteorologists warn.

The magnitude of the storm surge, waves and winds on the Outer Banks and southeastern Virginia will depend on how close to the coast Hurricane Erin tracks. Erin’s eye is forecast to pass at least 150 miles offshore. Because of the distance, little to no rain from Erin is forecast in eastern North Carolina. Still, impacts along the coast can be significant.

“People on the coast should not just focus on the eye track of a hurricane, especially one that is as large and strong as Hurricane Erin,” AccuWeather Lead Hurricane Expert Alex DaSilva said.

Due to Erin’s already large and growing zone of winds and waves, significant problems associated with a relentless storm surge, flooding and overwash from waves on top of the surge will lead to coastal flooding and erosion on the Outer Banks. The AccuWeather RealImpact™ Scale for Hurricanes in the U.S. is less than one, which will be equivalent to a strong tropical storm in terms of storm surge.

Officials have declared a State of Emergency for North Carolina’s Dare County, and mandatory evacuation orders have been issued for Hatteras Island, North Carolina.

Erin’s hurricane- and tropical-storm-force wind zone continues to expand. On Sunday morning, hurricane-force winds extended out 25 miles, and tropical storm winds reached 200 miles from the center. On Monday morning, hurricane-force winds had expanded out to 80 miles, and tropical storm winds were reaching 230 miles from the center.

The expansion of the wind field is due to a common phenomenon known as an eyewall replacement cycle.

“The strongest hurricanes experience this at least once in their lifetime, and some have it occur multiple times,” DaSilva said. “Erin experienced one such cycle over the weekend, with another taking place on Monday. The cycle initially knocks down the overall strength of the wind at the core, but then the hurricane gets a reboot and can regain wind intensity. The problem is, during each eyewall replacement cycle, the hurricane’s wind field expands in size.”

Erin is acting like a giant plunger over the ocean just northeast of the Bahamas. Waves produced by powerful winds in the storm continue to propagate outward.

Some uptick in wave action was already occurring along the southern Atlantic coast of the U.S. on Monday. Swells will continue to expand northward into the mid-Atlantic and New England.

Waves in the building surf zone will lead to an increase in the strength and number of rip currents. The dangerous conditions may cause many beaches to close.

As the week progresses, wave heights will build, and more ocean water will be pushed shoreward than has time to escape to sea–even with Erin’s core staying a couple of hundred miles offshore. This will lead to the storm surge.

The North Carolina Outer Banks will experience a storm surge of several feet with wave action on top of that, likely between 10 and 15 feet, depending on Erin’s eye proximity to the coast. The worst conditions are likely from late Tuesday to Thursday.

With these expected conditions, portions of North Carolina Highway 12 will experience significant overwash flooding and could be damaged. More homes on the barrier islands may be washed into the sea.

Late in the week, as Erin accelerates and moves northeastward, away from North Carolina, conditions will improve. However, it is possible that parts of the Outer Banks may be cut off depending on damage to the sandy soil and road surface of Highway 12.

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