More coastal nuisance flooding forecast

Posted at 8:16 AM, Sep 09, 2015
and last updated 2015-09-09 11:16:51-04

WASHINGTON (AP) — Federal scientists said Wednesday they expect nuisance flooding to increase in many places along the nation's coasts in coming months.

A combination of sea level rise from human caused global warming and the giant El Nino will likely combine to increase the type of minor street flooding that causes much inconvenience but no major damage, according to the National Oceanic and Atmospheric Administration.

In 10 of the 27 coastal communities that NOAA examined, scientists predict the number of nuisance flood days to increase 33 to 125 percent with the current large El Nino. And it's likely to be the worst in the Mid-Atlantic region where nuisance floods could happen about once a week from New Jersey to North Carolina. The nuisance flood season runs mostly from fall to early spring.

NOAA oceanographer William Sweet examined data going back to 1920 in some cases and found the flooding is not only increasing with climate change and rising seas, but "some of these areas you can get it with no rain at all — high-tide flooding."

These "sunny day flooding" events are becoming more common. For example, Wilmington, North Carolina, used to average one day of nuisance flooding a year in 1960 but between May 2014 and April 2015, that city had 71 such flood days, according to NOAA data. Annapolis, Maryland, went from four to 41 flood days and Sandy Hook, New Jersey, jumped from two to 21.

El Nino — a general warming of parts of the Pacific that changes weather worldwide — brings nuisance flooding to a new level. That's because in the Pacific, the ocean is warmer and warm water expands, Sweet said. In the Atlantic, the phenomenon brings more coastal-hugging storms and winds.

"Expect that sea level rise will progress like steps of a kitten, punctured by swipes of a lion," said Donald Boesch, president of the University of Maryland Center for Environmental Science, who wasn't part of the report.

Sweet is forecasting that with El Nino, Norfolk, Virginia, to go from about eight flood days to 18 this fall, winter and spring. Washington is forecast to jump from 33 to 53 nuisance floods days. Sandy Hook should get about 40 such days and Baltimore is likely to jump from two weeks of nuisance flooding to three weeks.

Sweet looked at increased nuisance flooding in Boston; Providence, Rhode Island; New London, Connecticut; Battery Park, Kings Point, and Montauk, New York; Atlantic City and Sandy Hook, New Jersey; Philadelphia; Lewes, Delaware; Baltimore and Annapolis, Maryland; Washington; Norfolk, Virginia; Wilmington, North Carolina; Charleston, South Carolina; Fort Pulaski, Georgia; Fernandina Beach, Key West and Mayport, Florida; Port Isabel and Galveston, Texas; La Jolla, California; San Francisco, Seattle and Honolulu.

The report by Sweet is not published in a peer reviewed journal, but four outside scientists examined it for The Associated Press and praised the work.

NASA oceanographer Bill Patzert, who wasn't part of the research, said the NOAA forecast "shows that the natural hazards don't necessarily have to be catastrophic like (hurricanes) Katrina or Sandy. They can creep up on you today. What is a nuisance today, in a couple decades will be a serious problem for some communities."