NEW YORK (CBSNewYork/AP) — A slower-than-usual hurricane season is expected this year because of an expected El Nino, federal forecasters said Thursday, but they warned that it takes only one storm to wreak havoc and urged Americans to be prepared.

The El Nino, which warms part of the Pacific every few years and changes rain and temperature patterns around the world, will likely reduce the number and intensity of tropical storms and hurricanes, the National Oceanic and Atmospheric Administration said in New York City.

“If there’s strong wind sheer, which is what El Nino produces, that strong change in wind direction and speed with height will either prevent a storm from forming or rip a hurricane apart if it moves into that region,” the NOAA’s Dr. Jerry Bell said.

Cooler temperatures on the surface of the Atlantic Ocean compared with recent years will also lower the probability of hurricane formation.

Officials expect about eight to 13 named tropical storms and three to six hurricanes. Just one or two major hurricanes with winds over 110 miles per hour are forecast.

“Three to six of which will become hurricanes and one to two of those may grow in strength to become category three or higher, major storms,” NOAA administrator Kathryn Sullivan told CBS 2’s Lonnie Quinn.

The six-month storm season begins June 1.

Forecasters got it wrong last year when they predicted an unusually busy hurricane season. There were just 13 named storms and two hurricanes, Umberto and Ingrid, both of which were Category 1, the lowest on the scale that measures hurricanes by wind speed. There were no major hurricanes.

In 2012, storm surge was devastating to the New York area when Superstorm Sandy slammed the East coast, killing 147 people and causing $50 billion in damage. Sandy lost hurricane status when it made landfall in New Jersey.

A new mapping tool this year will keep coastal residents updated on the storm surge threat in their communities. New York City residents can learn which of six evacuation zones they live in, as well as other info on hurricane preparedness, by visiting the city’s “Know Your Zone” website.

“It’ll say this is where water’s gonna come in, this is how high it’s going to be, how wet are you going to be; I mean that’s critical stuff,” said Commissioner Joseph F. Bruno of New York City’s Office of Emergency Management.

The Atlantic hurricane season goes through cycles of high and low activity about every 25 to 40 years based on large scale climatic patterns in the atmosphere. Since 1995, an average season has 15 named tropical storms, eight hurricanes and about four major storms. The last time a major hurricane made landfall in the U.S. was when Wilma came ashore in 2005, an eight-year stretch that is the longest on record.

Regardless of numbers, the overall message from the NOAA on Thursday was that residents can’t let their guard down, CBS 2’s Quinn reported.

“No percentage, no probability erases the fact that in hurricane season, any section of our coastline could be hit by a severe tropical storm and one storm can wreak tremendous havoc,” Sullivan said.

During the six-month season, forecasters name tropical storms when top winds reach 39 mph; hurricanes have maximum winds of at least 74 mph.

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