Insurers are years away from directly using a key atmospheric index to predict future European windstorms, according to the catastrophe data consortium PERIS AG.
The North Atlantic Oscillation Index (NOA) — which quantifies the pressure differences between sub-polar and sub-tropical zones that fuels many European winter storms — has limited long-term forecast relevancy and will be of little use in constructing insurance coverage, Zurich-based PERILS said in a quarterly newsletter.
“While forecasts of NAO conditions for entire winter seasons exist, their accuracy appears to be rather limited. Mid-term forecast, such as 14-day predictions of the NAO index, are more reliable, but are already factored into numerical weather predictions,” PERILS says. “It therefore appears that at present there is no silver bullet to enable us to predict the level of activity and intensity of future windstorm seasons.”
However, the article does argue it is “certain” that windstorm clustering correlated with phases of a positive NAO Index does exist and that further research may one day help to better anticipate the seasonal storm activity.
“The correlation of recent storm activity with NAO index values is simply an observation we (and others before us) made,” says PERILS CEO Dr. Luzi Hitz in an emailed statement. “In the long-term it might lead to more reliable seasonal forecasts of extra-tropical cyclone activity. That would be helpful for managing the Cat risk and this is why we raised the topic in our newsletter.”
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