Thunderstorms Pose as Much Property Risk as Hurricanes

Thunderstorms Pose as Much Property Risk as Hurricanes

Risk to U.S. property from thunderstorms is as high as from hurricanes, according to new research published by Willis Re, the reinsurance division of Willis Towers Watson, the global advisory, broking and solutions company.

A report compiled with Columbia University, a member of the Willis Research Network (WRN), Managing Severe Thunderstorm Risk, says that the average annual loss from severe convective storms (SCS) was $11.23 billion, compared with $11.28 billion from hurricanes for the period 2003–2015. For the past decade, SCS was the largest annual aggregated risk peril to the US insurance industry.

The report also says that SCS frequency in the U.S. is higher following La Niña, and lower following El Niño.

Prasad Gunturi, executive vice-president, Willis Re said: “Regional variability in increased or reduced severe convective storm frequency due to the El Niño-Southern Oscillation (ENSO) phase can have a significant impact on regional and single state property insurance companies. In collaboration with Columbia University, we are working to develop a climate conditioned severe convective storm event set for portfolio probabilistic loss estimates. We hope the climate conditioned view of risk can help companies understand, manage and mitigate the regional and year over year variability in severe convective storm losses.”

Michael Tippett, associate professor in Columbia Engineering’s Department of Applied Physics and Applied Mathematics, said: “The latest research shows that ENSO and other climate signals modulate the frequency of tornado and hail activity in the U.S. We’re excited to be using that research as a scientific basis for making long-range (up to a month) forecasts of the meteorological factors that go along with severe convective storms.”

The report was written to increase understanding of the impact of ENSO on tornado and hail frequencies, and to introduce the concept of ENSO-conditioned event rates. Using data from Columbia researchers, Willis Re now plans to produce monthly forecasts of tornado and hail activity for client use.

Other Columbia University contributors to the report are Chiara Lepore of Lamont-Doherty Earth Observatory and Adam Sobel of the Fu Foundation School of Engineering and Applied Sciences and Lamont-Doherty Earth Observatory, and director of Columbia’s Initiative on Extreme Weather and Climate.

Adapted from a Willis Re and Columbia University press release.