Hurricane Sandy churns off the Atlantic coast on Oct. 29. NOAA officials are forecasting seven to 11 hurricanes, compared with about six in a typical season.
Unusually warm ocean temperatures and favorable wind patterns mean the Atlantic is likely to see "an active or extremely active" hurricane season this year, say officials from the National Oceanic and Atmospheric Administration.
The agency expects between seven and 11 hurricanes and as many as 20 named storms during the 2013 season, which runs from June 1 through November.
So for residents of the Atlantic and Gulf coasts, "now is the time to pay attention to preparedness," NOAA's acting administrator, Kathryn Sullivan, told a news conference Thursday at the agency's new Climate Prediction Center in College Park, Md.
Extreme weather can be deadly, Sullivan and other officials at the event stressed. "Our hearts go out to the people in the communities in Oklahoma, who as we join here today to talk about hurricanes, are still recovering from Monday and Tuesday's devastating tornadoes," Sullivan said.
Tornadoes, like the one that ripped through Moore, Okla., can produce winds that are more intense than those of hurricanes. But hurricanes generally cause more damage and loss of life because they can cut a swath of destruction that is hundreds of miles across.
In an average year, about six hurricanes and 12 named storms form in the Atlantic Ocean and Caribbean Sea. But this year is likely to be more active than normal for at least two reasons, say forecasters.
One reason has to do with the temperature of the water where hurricanes tend to form. "The tropical Atlantic is very warm, much warmer than normal," says Phil Klotzbach of Colorado State University. "And since hurricanes live off of warm ocean water, we expect to see more tropical cyclones and probably more intense [ones] than an average season."
Another factor is the lack of so-called El Nino conditions, which occur when waters in the tropical Pacific heat up. An El Nino tends to produce wind patterns that tear apart Atlantic hurricanes as they approach the U.S.
Last year at this time, many forecasters believed an El Nino was on the way, says Dan Leonard of Weather Services International. "And then in reality, El Nino wasn't as strong as we initially thought."
So there were lots of storms, including 10 hurricanes. But most of them turned away from the East Coast as they encountered strong winds from the jet stream, Leonard says.
Government forecasters say it's hard to know whether those winds will continue in 2013. But Leonard says he sees some evidence that they will.
"We think we'll have a pretty active jet stream, and that should deflect a lot of these storms back out to sea," he says, adding "that's not to say that one can't sneak through as we saw happen last year with Sandy."
Sandy struck the New York and New Jersey coast in late October and became the second-costliest hurricane in U.S. history. At the NOAA news conference, Sullivan urged people to think back to that storm as they prepare for the upcoming season.
"With the devastation of Superstorm Sandy fresh in our minds and another active season forecast," Sullivan said, "we again encourage families and businesses in states along the Gulf and Atlantic Coast and inland from those areas to take time now to make or refresh their hurricane preparedness plans."