“Hurricane” Hal Needham is a storm surge scientist who specializes in data-driven storm surge analysis. He is the founder and president of Marine Weather and Climate.
A prolonged storm surge event is underway along the Eastern Seaboard. A strong pressure gradient between a dome of high pressure over Canada and Hurricane Joaquin near the Bahamas is producing a sustained northeast wind from North Carolina to New England.
As of 8 a.m. Eastern time, storm surge levels exceeded 2 feet above predicted tide levels from North Carolina through Southern New Jersey. Several sites near the mouth of the Delaware Bay and Chesapeake Bay reported storm surge levels between 2-3 feet. The highest storm surge level observed by NOAA's National Ocean Service (NOS) tide gauges was 3.05 feet, at Wachapreague, Va.
As this wind and surge event will last for at least four days, storm surges will be added to at least eight high tide cycles. The most noticeable flooding will occur near the time of high tide.
High tide will occur just after noon today for much of the Mid-Atlantic Coast. In most places, high tide occurs approximately every 12.5 hours, so it will occur again Saturday morning after midnight, and again early afternoon on Saturday. High tide in bays and coastal inlets often occurs around an hour after peaking at the coast.
At Wachapreague, Va., high tides should occur around 12:30 p.m. today, 1 a.m. Saturday, and again around 1:30 p.m Saturday. The difference between low and high tide at this site exceeds 4 feet.
The regional surge map shown at the top of this blog post depicts surge levels at precisely 8 a.m. Eastern time. Keep in mind that even if those surge levels do not increase, as high tide approaches, coastal inundation should be more noticeable. Stay tuned to your updates from your local National Weather Service office, and the National Hurricane Center for more updates on this developing event.