U.S. government meteorologists predict a "possibly extremely active" hurricane season in 2013, the top National Oceanic and Atmospheric Administration official said Thursday, with as many as half a dozen major hurricanes.
NOAA expects 13 to 20 named tropical cyclones, seven to 11 of them reaching hurricane status, with maximum winds 74 mph or higher. Of those hurricanes, three to six could become major hurricanes, with winds of at least 111 mph.
The forecast echoes outlooks released earlier this spring calling for another active hurricane season, which starts June 1 and ends Nov. 30. It continues an active trend stretching nearly two decades.
Acting NOAA Administrator Kathryn Sullivan urged residents living along the Atlantic and Gulf of Mexico coasts to prepare for storms, though the forecast could not show where storms might have the strongest likelihood of making landfall, she said.
"If you live along those shorelines, this is your warning," Sullivan said at a media event, held at NOAA's Center for Weather and Climate Prediction in College Park. The event is often held in Florida and other locations but was moved to Maryland this year in part to showcase the new facility, which opened last fall and is where the hurricane outlook and other climate forecasts are developed.
Conditions are expected to be ripe for hurricane development, with warm Atlantic water temperatures, lower atmospheric pressure, smaller differences in wind speeds at varying altitudes and favorable wind patterns, forecasters said. Cool Pacific Ocean temperatures could also translate to a busy Atlantic storm season because they indicate the absence of El Niño, a climate phenomenon known to stunt tropical cyclone development.
Many such conditions have been in place in the Atlantic since about 1995, with a trend toward more active seasons over the past two decades, Sullivan said.
Five of the past seven seasons since a record-setting 2005 season have been more active than normal. There have been 19 named storms each of the past three years, while a dozen is considered normal. There were 28 storms in 2005, the year of Hurricane Katrina and the most active season on record for the Atlantic.
Although there were a large number of named storms in 2012, there were few strong storms — other than "superstorm" Hurricane Sandy. Sandy was one of two major hurricanes last year.
AccuWeather.com is predicting fewer storms overall, with 16 tropical storms versus 19 in 2012, but more major hurricanes, with four.
"After a devastating blow to the East from Superstorm Sandy in October of 2012, residents and homeowners on the Atlantic coast should anticipate another active season in 2013," the forecast warned.
Forecasters at Colorado State University predicted 18 named storms would form in the Atlantic Ocean, about six more than normal but one fewer than in 2012. They expect nine of those storms to become hurricanes, and are also calling for four of those hurricanes to reach "major" storm status.
While the hurricane season outlooks look largely at climate conditions influencing tropical cyclone development, the National Hurricane Center will meanwhile have a few new tools to better study individual storms, Sullivan said.
A new supercomputer that will allow for more complex and potentially more accurate forecast models will be ready to use by July, she said. Meteorologists will also for the first time be able to feed models with real-time radar captured by "hurricane hunter" planes as the aircraft fly through tropical storms and hurricanes, she said.
Where storms develop and whether they make landfall depend on specific weather patterns over the U.S., however, said Gerry Bell, lead hurricane forecaster with NOAA's College Park facility.
This season's first storms will be named Andrea, Barry and Chantal.