Plan on another abnormally busy storm season – the fourth in a row, Phil Klotzbach and William Gray say.
Their 2013 Atlantic hurricane season forecast: 18 named storms, including nine hurricanes, four major. The average season sees 12 storms, including six hurricanes, three with winds greater than 110 mph.
The two Colorado State University climatologists say the tropical Atlantic is unusually warm and El Niño, the atmospheric force that inhibits storm formation, is unlikely to emerge this season, which starts June 1 and runs through Nov. 30.
“Typically, El Nino is associated with stronger vertical shear across the tropical Atlantic, creating conditions less conducive for storm formation,” Klotzbach said.
Another factor: The Atlantic basin remains in an era of tropical intensity, where more hurricanes tend to form, the result of a natural cycle, they say.
Jeff Masters, chief meteorologist of Weather Underground, an online weather site, said years where neither El Niño nor its polar opposite, La Niña, emerge can be highly active.
“Remember the neutral El Niño year of 2005?” he said, referring to the season when 28 storms, including 15 hurricanes, formed.
On the other hand, he noted, “if El Niño conditions are present this fall, this will likely bring about a quiet Atlantic hurricane season.”
Klotzbach and Gray put the odds of at least one major hurricane striking the U.S. East Coast at 48 percent, vs. the long-term average of 31 percent. For the entire U.S. coastline, they put the odds at 72 percent; the long-term average is 52 percent.
Florida, by far the most storm-battered state, has escaped a hurricane hit for a record seven seasons, since Wilma struck in October 2005.
Although the actual numbers of storms they predict are rarely right on target, Klotzbach and Gray have accurately predicted when a season would be more or less active than normal in four of the past five years.
They botched their initial prediction for 2012 last April, calling for a considerably slower than normal season. Like other prediction teams, they thought El Niño would arise by the heart of the season.
However, it didn’t and the year ended with 19 named storms, including 10 hurricanes. That made it the third busiest season on record, tied with 1887, 1995, 2010 and 2011.
Several other forecast teams are expected to release seasonal outlooks over the next two months, including AccuWeather.com and WSI, a part of The Weather Channel. The National Oceanic and Atmospheric Administration will release its predictions on May 23.
Klotzbach and Gray say they develop the forecasts to give coastal residents an idea of what they might be up against.
“All vulnerable coastal residents should make the same hurricane preparations every year, regardless of how active or inactive the seasonal forecast is,” Klotzbach said.
Here’s a look at how Phil Klotzbach and William Gray’s April predictions have fared against reality in the past five years:
Prediction: 10 named storms, four hurricanes, two major