Washington ? Batten down the hatches for hurricane season.

Forecasters expect more tropical storms than normal, and “it just takes one to make it a bad year,” says Conrad Lautenbacher, head of the National Oceanic and Atmospheric Administration.

National Weather Service forecasters said Tuesday they expect 13 to 17 tropical storms, with seven to 10 of them becoming hurricanes and three to five in the strong category. NOAA is the parent agency of the weather service.

David Paulison, director of the Federal Emergency Management Agency, said what keeps him up at night is concern about individual preparedness.

“If we are going to survive these storms, it takes all of us to be ready,” Paulison said, urging that the millions of residents in vulnerable areas prepare their homes for the storms and keep at least three days’ food and supplies on hand.

After the battering by storms Katrina and Rita in 2005, there were widespread fears last summer of another powerful storm striking, but the unexpected development of the El Niño climate phenomenon helped dampen conditions.

El Niño is a warming of the tropical Pacific Ocean that occurs every few years. The warm water affects wind patterns that guide weather movement and its effects can be seen worldwide. In El Niño years, there tend to be fewer summer hurricanes in the Atlantic Ocean.

But El Niño is over, and conditions could develop that might even encourage more storms, said Bill Proenza, head of the National Hurricane Center.

Earlier this month Philip Klotzbach, a research associate at Colorado State University, and Joe Bastardi, the chief hurricane forecaster for AccuWeather Inc., said they anticipate a more active storm cycle this year.

And, almost as if to underscore their comments, a subtropical storm formed off the Southeast coast and became Andrea, the first named storm of the year, well before the June 1 official beginning of hurricane season.

Hurricane season ends Nov. 30, but the strange season of 2005 ran over into late December, as well as using up all the planned alphabetical names, forcing storm watchers to switch to the Greek alphabet to continue naming storms.

Last year, there were just 10 tropical storms in the Atlantic and only two made landfall in the United States.

While last year proved quieter than expected and 2005’s parade of storms caused the weather service to raise its prediction, the number of tropical storms predicted in May was within the expected range in 1999, 2000, 2002 and 2004. The forecast was low in 2001 and 2003.