Guy Carpenter highlights hurricane factors

  • Busy year: the 2017 North Atlantic hurricane season was the seventh most active in recorded history. A number of meteorological factors came together to increase the frequency and strength of storms

There were a number of key meteorological factors that contributed to last year being one of the most active and damaging North Atlantic hurricane seasons in history.

Hurricanes Harvey and Irma accounted for a significant portion of the $306 billion of economic losses sustained by the US in 2017 as a result of natural catastrophes, which also included major wildfires in western states.

Many parts of the Caribbean were badly affected by hurricanes Irma and Maria.

With 10 hurricanes, including two category 5 and one category 4, the 2017 season was the seventh most active in recorded history in the North Atlantic.

Meteorological factors that converged to help produce such an active season included very warm sea-surface temperatures, abnormally reduced wind shear, and increased moisture for key areas.

According to James Waller, a research meteorologist at Guy Carpenter’s GC Analytics: “This enabled hurricane development and in some cases rapid intensification. Furthermore, the Atlantic subtropical ridge extended further west than was previously observed for most of the 2006-2016 period.

“The westward extent of the ridge in 2017 tended to suppress storm recurvature until storms had drifted further west, such as occurred with Irma and Maria.”