December is fast approaching, and in much of North America and Europe the crisp days and golden colors of autumn are giving way to a world of sparkling lights, frenzied shoppers, and the sense of merriment that comes with the onset of the festive period. At this time of year, an equally marked transition takes place within the catastrophe risk management community, as the Atlantic hurricane season closes and attention shifts to the onset of the December to February (or, in meteorological parlance, DJF) peak season for European windstorm risk.
However, three notable early season wind events have already impacted Europe during the earlier part of this current windstorm season. These are windstorm Xavier (October 5; Germany, Poland, and Czech Republic), ex-hurricane Ophelia (October 16; Ireland), and windstorm Herwart (October 29; Germany, Poland, Czech Republic, and Austria). The earliest of these, Xavier, formed just one day after the Category Five Hurricane Maria dissipated — at a time when the attention of the global insurance market was firmly focused on the other side of the Atlantic.
Known indicators point to stormier conditions in the North Atlantic this winter. However, what this means for Europe windstorm losses is much less certain.
Our ability to understand and forecast variability of North Atlantic winter storminess continues to improve year-on-year. Research highlights in 2017 include:
- A new, and skillful, empirical forecast model for winter climate in the North Atlantic revealed that sea ice concentrations in the Kara and Barents Seas are the main source of predictable winter climate variations over the past three decades. Interestingly, a separate 2017 study supports earlier forecasts of either a slowing or reversal of the sea ice reductions in the Barents and Kara Seas between now and 2020, implying an uptick in storminess over the next few years.
- An innovative tool to analyze sources of predictability in a numerical forecast model revealed strong links between tropical climate anomalies and winter climate in the North Atlantic in that model.
Twelve months ago, the forecasting indicators for the windstorm season broadly pointed to a 2016/17 season characterized by below average storminess — a forecast borne out by subsequent observations. We have already had a fairly active start to the 2017/18 season, with Windstorms Xavier, Herwart, and ex-Hurricane Ophelia causing local damage, but what is the outlook for the rest of the season?