Coastal storm comes together, forecast to lash North Carolina and the mid-Atlantic beginning today

Warnings issued from North Carolina to the Delmarva, including parts of Chesapeake Bay, ahead of the strengthening storm system

Sunrise satellite Friday morning showing Potential Tropical Cyclone 16 off the southeast U.S. coast. Credit: NOAA.

On Thursday, the National Hurricane Center issued tropical storm warnings ahead of a large coastal storm coming together off the southeast U.S. coast.

The non-tropical low-pressure system – designated a Potential Tropical Cyclone by the NHC for the possibility of it transitioning into a hybrid tropical system – is set to deliver a stinging shoreline punch from eastern North Carolina northward through the Delmarva starting today into Saturday.

Whether the coastal storm acquires enough tropical characteristics to meet the criteria of a subtropical storm is practically insignificant, as the impacts won’t change. Gusty tropical storm force winds (39 mph or stronger) up to 60 mph should be expected in the warned areas, with dangerous seas, life-threatening rip currents, battering surf, and widespread coastal flooding around the times of high tide.

A storm surge warning is in effect for North Carolina’s Outer Banks and Pamlico and Albemarle Sounds into the Virginia Tidewater and lower Chesapeake Bay for possible life-threatening coastal flooding of up to 3-5 feet in low-lying coastal areas.

Though the heavy rainfall threat is secondary to the marine and storm surge hazards, rainfall totals of 3 to 6 inches may produce pockets of flash flooding from late today through Saturday evening across eastern North Carolina, southeast Virginia, and the southern Delmarva Peninsula.

The coastal storm is expected to cross the North Carolina coast on Saturday and move northward into the Chesapeake Bay, eastern Maryland, and the DC area for late Saturday into early Sunday where high water could affect the Old Town Alexandria, Southwest DC, and Annapolis Waterfronts. The wide reach of the storm system will also impact coastal New Jersey and parts of the northeast with disruptive weather – including widespread coastal flooding – beginning tonight into Saturday.

Invest 90L expected to develop, but forecast trends encouraging for the islands

The tropical wave we’ve been following this week – designated Invest 90L by the National Hurricane Center yesterday – continues to gradually organize. The disturbance is likely to become a tropical storm by early next week as it heads westward across the deep tropical Atlantic.

Models have come into better agreement for next week, bending the strengthening storm northward before reaching the islands of the eastern Caribbean. Intensity models suggest this will become our next hurricane, but if early forecasts materialize, it may miss land like recent Hurricanes Nigel and Margot.

Global model probabilities of Invest 90L passing within 100 miles of a given location. Models have trended toward a future track bending north of the islands by the middle of next week. Credit: Tomer Burg/University of Oklahoma

The storm would not make its closest approach to the islands until middle of next week, so interests in the Lesser Antilles should continue to monitor the forecast for any changes.

Elsewhere in the Atlantic

Nigel finished up its time as a tropical cyclone and is speeding into the far reaches of the North Atlantic as an extratropical cyclone.

For now, the last week of the hurricane season’s busiest month is looking to close without any concerns for South Florida. Readers are encouraged to stay vigilant into October, as South Florida is especially susceptible to hurricane threats in early fall as fronts can pull systems northeastward and toward the Sunshine State out of the still-warm Caribbean.

About the Author:

Michael Lowry is Local 10's Hurricane Specialist and Storm Surge Expert.