WASHINGTON — 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 increase the type of minor street flooding that causes much inconvenience but no major damage, according to the National Oceanic and Atmospheric Administration.

Sea level rise and El Nino will likely result in more minor street flooding that causes inconvenience but no major damage, the National Oceanic and Atmospheric Administration says. The Associated Press

In 10 of the 27 coastal communities that NOAA examined, scientists predict the number of nuisance flood days to increase 33 percent 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, averaged one day of nuisance flooding 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.

Sweet is forecasting that with El Nino, Norfolk, Virginia, will 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.

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