Eastern Storm Could Produce Worst Tidal Flooding in Mid-Atlantic in Years

 Jonathan Erdman

Published: October 29, 2021

A sprawling Eastern storm, the second in a week, will soak the Mid-Atlantic and Northeast, but its most serious threat will be wind-driven major coastal and tidal flooding that could be the highest seen in 18 years in some areas.

This expansive low-pressure system is currently spinning over the Ohio Valley, with a broad area of rain rotating around it from the Great Lakes and Mississippi Valley to the Tennessee Valley to the mid-Atlantic and Northeast.

We'll discuss the rain impacts of this storm a bit later.

It's the storm's winds, and the impact of those winds, that is the biggest concern.

Winds Will Pile Water Ashore

Several days of onshore winds from the nor'easter earlier this week kept water levels elevated along the coast, bays, etc.

Now, strong easterly winds are pounding parts of the Mid-Atlantic through Friday night.

The National Weather Service has issued high wind warnings for the southern New Jersey and Delaware Atlantic coasts, where gusts up to 60 mph could lead to tree damage and power outages.

But those easterly winds are also pushing water from the ocean into bays, inlets and tidal rivers. That will likely be the biggest impact from this storm.

Coastal flooding already occurred with Friday's high tide in eastern Virginia's "Northern Neck", south of Washington, D.C., according to video posted to social media.

Flooding also closed streets, sidewalks and docks in and near Annapolis, Maryland, Friday.

And some homes and structures were reportedly taking on water at Solomon's Island, about 50 miles southeast of Washington, D.C. at the mouth of the Patuxent River, according to Calvert County emergency management.

This coastal and tidal flooding will peak from Friday into early Saturday but may linger into later Saturday or even Sunday before winds turn offshore and allow water levels to gradually fall.

While the most significant flooding will occur at high tide, additional minor to moderate flooding may occur even at low tide in some areas.

If that wasn't enough, some of these areas are expected to pick up around an inch of rain. With rivers slow to drain, this will only add water to the tidal/coastal flood headache.

It may also trigger local flash flooding in other parts of the Northeast not experiencing coastal/tidal flooding.

Highest Storm Tides In Over a Decade Possible

A number of locations are expected to see major flood crests along tidal rivers, such as the Delaware River, and the Chesapeake Bay.

In these areas, the flooding could not only flood typical streets near the water, but also submerge homes, businesses and vehicles in 2 to 4 feet of water.

According to the National Weather Service, some evacuations may be needed in parts of eastern Virginia.

Forecast peak flood stages from the National Weather Service, color-coded by severity, through Saturday.

Some of those flood crests could be among the highest seen in years.

Along Delaware Bay at Reedy Point, Delaware, south of Wilmington, Friday evening's crest could top the record from April 2011, in records dating to at least 1980.

According to the National Weather Service, flooding in Baltimore's harbor and some areas of Maryland's Eastern Shore could see the highest flood crests since Hurricane Isabel in 2003.

In Annapolis, Maryland, flooding may reach levels topped only by Isabel and an August 1933 flood, putting the city's boardwalk at the city dock underwater. Moderate flooding may last, there, into Saturday.

In Philadelphia, the Delaware River could crest Friday evening over a half a foot higher than it did during the remnant of Hurricane Ida on Sept. 1, comparable to flooding in Dec. 2012. The Schuylkill River, however, will remain well below levels seen during the torrential rain from Ida.

In the Washington, D.C. metro, a pair of high tides Friday and early Saturday morning in Alexandria, Virginia, will be several inches higher than the April 2011 and Sept. 2018 floods, exceeded only by Isabel and a March 1936 flood, inundating lower portions of several streets.

Friday afternoon's high tide flooded and closed the George Washington Parkway south of Alexandria, something WTOP Radio reported was rare. Water inundated The Wharf in D.C. requiring workers to use boats to navigate, WTOP reported.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.