Friday, October 2, 2015

Surge Levels Now Exceed 3 ft at Five Locations between Delaware and Chesapeake Bay

Storm surge levels continued to rise this evening as a persistent onshore wind continues to blow from the northeast from North Carolina through New England.

Surge levels are now > 3 ft for at least five locations between Delaware and Chesapeake Bay. The total water level, or storm tide (surge + tide) should continue to rise in most locations as high tide approaches most coastal areas around 1:00AM Eastern Time Saturday. High tide will occur a little later on bays and inlets.

Low tides should be observed around daybreak Saturday, with high tides occurring again around 1:30PM Eastern Time at the coast.

Storm surge observations as of 1000 PM Eastern Time on Fri Oct 2. These data are provided by NOAA Tides and Currents.

A 3-ft storm surge has a greater impact than one might expect because of the following:

1. The tidal range across much of this region is 4-5 feet between low tide and high tide. Adding 3 ft to the high tide level will cause coastal inundation in many low-lying areas.

2. Elevated coastal water levels slow the drainage of heavy rainfall, because most drainage systems are gravity fed. A prolonged storm surge can cause fresh water flooding from 1-2 inches of rain, when typically that much rain runs off quickly.

3. The prolonged nature of this wind/ surge event means storm surge will be added to at least eight high tide cyclones. Such persistent conditions will likely cause much more coastal erosion than usually experienced from a 3-4 ft surge.

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