Forecasters at Colorado State University are declaring this year's Atlantic basin hurricane season to be an unusual one that had more activity than expected, but with virtually all of that activity coming in the form of weaker storms.

In a report issued today by the hurricane forecast team led by Phil Klotzbach and William Gray, the 2012 hurricane season, which officially ends tomorrow, "was one of the most unusual seasons on record with a significant number of weaker cyclones combined with a general lack of major hurricane activity…."

In August, the team issued an updated forecast calling for average activity: 14 named storms, six hurricanes and two major hurricanes.

The season produced 19 named storms, 10 hurricanes and only one major hurricane.

The team notes that no major hurricanes made landfall in the United States this past season. A major hurricane is defined as a Category 3, 4, or 5 tropical cyclone on the Saffir-Simpson scale, with sustained winds of 111 mph and higher.

Despite its size, with a wind radius of close to 500 miles, Superstorm Sandy never reached major hurricane status. However, when it made landfall as a post-tropical storm it generated the lowest pressure ever recorded in the Northeast U.S. at 943 millibars, breaking the record set by the Great New England Hurricane or Long Island Express of 1938, the Colorado team says.

The report goes on say that Sandy "has the potential to be the most economically destructive storm the United States has ever had, with total economic damage expected to exceed $100 billion dollars.

Touching on a topic recently covered by PC360 regarding whether Sandy was caused by the effects of climate change, Gray says, "Although storms such as Sandy are extremely rare, these types of tropical cyclones are well within natural variability, and should not be attributed to increases in human-induced greenhouse gases."

The CSU team plans to release a more in-depth discussion of Sandy and its potential relationship to climate change by the end of the week.

The National Oceanic and Atmospheric Administration released its assessment of the Atalantic hurricane season today saying it classifies 2012 as above-normal, but not exceptionally so because there were 10 busier years in the past three decades.

However, it was the second consecutive year that the mid-Atlantic and Northeast suffered "devastating impact from a named storm."

"Sandy, and Irene last year, caused fatalities, injuries, and tremendous destruction from coastal storm surge, heavy rainfall, inland flooding, and wind," says NOAA. "Storms struck many parts of the country this year, including tropical storms Beryl and Debby in Florida, Hurricane Isaac in Louisiana, and post-tropical Cyclone Sandy in New Jersey."

NOAA also notes that the year was marked by two storms, Alberto and Beryl, developing in May before the start of the season.

The number of named storms was higher than predicted in large part because an El Niño that was expected to form in the Pacific, which would have suppressed overall storm activity, never formed.

Updated with additional comment from NOAA

Special Reports /

Unusual Hurricane Season Produces More Storms Than Expected

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