When you hear a weather forecast, especially a long-range one, are you skeptical? Most people are, but sometimes the forecasts can be believed. The Colorado State University (CSU) team predicted a below-average Atlantic hurricane season for 2014, and they were right! That’s good news for P&C insurers as well as flood carriers, who can breathe a sigh of relief that the season’s over.

The CSU team originally predicted nine named storms, three hurricanes and one major hurricane. The prediction was later revised to 10 named storms, four hurricanes and one major hurricane. The actual tally for the 2014 Atlantic basin hurricane season from June to November is eight named storms, six hurricanes and two major hurricanes, according to the 2014 report funded by Interstate Restoration and Ironshore Insurance.

The CSU Tropical Meteorology Project team of Phil Klotzbach and William Gray also closely predicted the seasonal Accumulated Cyclone Energy (ACE), which approximates the energy generated by all the storms that form during a particular year. ACE is considered to be a better measure for overall storm activity than the number of named storms or hurricanes. Klotzbach and Gray called for 65 units and the ACE for 2014 was recorded at 66 units.

31 years of forecasting hurricane activity

The team, which has been issuing forecasts for the past 31 years, bases its annual forecasts on 60 years of historical data and includes factors such as Atlantic sea surface temperatures and sea level pressures, levels of vertical wind shear (the change in wind direction and speed with height), El Nino (an analogous warming of waters in the central and eastern tropical Pacific Ocean) and other factors.

Gray & Klotzbach

“It’s remarkable that we have not had a major hurricane make landfall in the United States for so many years,” Klotzbach said in a statement. “Steering currents have been such that hurricanes moving toward the U.S. have recurved out to sea before reaching the coastline.” For those who lived through Superstorm Sandy, this comment may seem inaccurate, but when Sandy made landfall in the U.S., it was considered a “post-tropical cyclone with hurricane force winds” according to the National Oceanic and Atmospheric Administration, better known as NOAA.

Overall, however, the Atlantic basin has experienced an increase in major hurricane activity since the mid-1990s, according to the team. From 1995-2013, the basin has averaged 3.5 major hurricanes per year compared to 1.5 per year from 1970-1994.

Klotzbach and Gray attribute the upturn in major hurricane activity since 1995, as well as the earlier increase in major hurricane activity from the late 1940s through the mid-1960s, to natural variability in the strength of the Atlantic Multidecadal Oscillation (AMO) or Atlantic Thermohaline Circulation (THC).

Certain factors influence hurricane activity

When the AMO/THC is positive, a variety of large-scale factors known to influence hurricane activity such as sea surface temperatures (SST), sea level pressures and vertical wind shear tend to be in a mode that’s favorable for hurricane formation. They tend to be in a mode unfavorable for hurricane formation when the AMO/THC is negative, explains the CSU team.

Storm warning sign

Although the past two years have had below-average Atlantic basin activity, the recent return to warm SST anomalies in the North Atlantic leads the team to believe that the THC/AMO is still stronger than normal.

A brief qualitative outlook for the 2015 hurricane season will be issued on Dec. 11 with a first full forecast for next season issued on April 9, 2015. Given the team’s successful track record, insurers and property owners should be eagerly awaiting the 2015 predictions.

Special Reports /

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