Gusty winds, coastal flooding among threats from potential subtropical storm

AccuWeather meteorologists continue to track an area of disturbed weather off the Atlantic coast of the United States that could take the final name of the 2021 Atlantic hurricane season's designated list, Wanda.

"An area of low pressure continues to meander off the Carolina coast and poses the only tropical threat over the next few days in the Atlantic basin," AccuWeather Meteorologist Thomas Geiger said.

This tropical low, just 90 miles south of Camp Hatteras, N.C., was producing gale-force winds early Sunday morning when the National Weather Service sent an aircraft through it. The NHC has dubbed this low pressure "92L".

"The storms associated with this system are disorganized at the moment and not particularly strong due to southerly wind shear," explained Geiger.

It has a 30% chance of becoming a cyclone over 48 hours, the NHC said.

Vertical wind shear, very influential for tropical cyclone formation, is the change in direction and speed of winds at increasing heights in the atmosphere. When it is present, the top of a tropical system can be blown hundreds of miles downstream and the storm can become very lopsided or tilted.

"The storm is running out of time to intensify as it will push up against the North Carolina coast on Sunday night," added Geiger.

The friction that occurs when tropical entities move near or over land can cause them to lose wind intensity and hinder development. Tropical systems strengthen the quickest over warm water.

Despite these obstacles, forecasters say there is still a small window of development, but perhaps not of tropical nature. Wind shear is expected to decrease slightly across the area Sunday, though conditions will still be far from conducive for tropical development.

"If it does form it will likely be classified as subtropical, given that it is showing some larger-scale features, and be given the name Wanda, which would finish up the 2021 name list," Geiger said.

This completion of the name list has only occurred twice before, once in 2005 and again in 2020, when those seasons were more active than usual. In the past, the NHC used the Greek alphabet to name extra storms, but this year could be unique.

"This would be the third time that all the names have been used, and it would be the first time the new supplemental name list is used if another storm forms this year," Geiger said.

Regardless if this storm receives the name Wanda or not, stormy and unsettled conditions are anticipated up and down the East coast this week.

"Heavy rain over eastern North Carolina will range from 2 to 4 inches, leading to flooding in spots," Geiger said.

High winds of onshore flow are also forecast along the coast, triggering coastal flooding. In spots most vulnerable to this impact, there could be as much as 1 to 2 feet of water above ground level, according to Geiger. High tides are also likely to enhance flooding.

Coastal flood watches, warnings, statements and advisories have been issued across much of the Atlantic Coast. Locations under coastal flood advisories include Georgetown, S.C.; Kitty Hawk, N.C.; Chincoteague, Va.; Ocean City, Md.; and New Haven, Conn. Boston is under a coastal flood statement, while coastal flood watches and warnings are in effect for much of coastal Virginia, parts of the New Jersey coast and portions of Delaware.

In these advisories, the National Weather Service warned motorists of partial or full road closures, especially the most vulnerable roadways. Warnings suggest many roads can become impassable and damage to structures can occur. People are urged to avoid leaving a vehicle at a location that is prone to tidal flooding and to never drive through floodwaters.

Dangerous rip currents will also be a concern across the coast, and forecasters suggest beachgoers avoid the water for the time being and follow all local instructions when it comes to ocean safety.

In addition to coastal concerns, rain and showers are expected across parts of the Northeast and mid-Atlantic on Sunday from North Carolina to Massachusetts as the low pressure approaches. The New York City area can expect cloudy, breezy and cool conditions with a shower or two in spots. Closer to the coast, steadier rain and drizzle are anticipated.

Monday, showers will continue to be spotty and contained by the coast from the Jersey Shore southward. Elsewhere will be generally dry. This spotty shower pattern can continue along the coast through the early week.