WASHINGTON, July 15 (UPI) -- A strong El Nino in future years could threaten the U.S. east coast with rising sea levels and more destructive storm surges, a study says.

The National Oceanographic and Atmospheric Administration study examined water levels and storm surge events during the "cool season" of October to April for the past five decades at four sites representative of much of the east coast, a NOAA release said Friday.


The sites were Boston, Atlantic City, N.J., Norfolk, Va., and Charleston, S.C.

In strong El Nino years between 1961 and 2010, these coastal areas experienced nearly three times the average number of storm surge events, the study found.

"High-water events are already a concern for coastal communities. Studies like this may better prepare local officials who plan for or respond to conditions that may impact their communities," NOAA researcher Bill Sweet said.

"For instance, city planners may consider reinforcing the primary dunes to mitigate for erosion at their beaches and protecting vulnerable structures like city docks by October during a strong El Nino year."

El Nino conditions are characterized by unusually warm ocean temperatures in the Equatorial Pacific that normally peak during the Northern Hemisphere "cool season."

They occur every three to five years with stronger events normally occurring every 10-15 years, NOAA said.