Extrapolation from wind extremes: pitfalls and surprises

Transient weather systems of the extra-tropical regions occasionally give rise to extreme wind conditions that cause a lot of material damage and loss of lives.
Estimating wind speeds for long return periods from observational records of order 50~years needs statistical methods that are hard to verify. Here we show, with the aid of an ensemble of 37 climate realizations with a climate model, that (transformed) annual maximum wind speeds can well be represented by a Gumbel distribution all over the globe (except the tropics) up to return periods of 10$^5$~years. These results confirm an earlier analysis of the observational ERA40 dataset.
The most exceptional wind extremes outside the tropics are caused by the interaction of a surface cyclone with the left exit of a (strong) upper-level jet stream, a similar mechanism that led to the exceptionally strong storms 'Lothar' and 'Martin' in december 1999 over France.