ABSTRACT
In general terms, there seem to be some general principles that reduce confusion in the estimation of extremes. Firstly, it is better not to mix mechanisms. If strong winds are generated by cyclonic weather systems and by thunderstorms, separation of the two types of data reduces errors. A study of thunderstorm activity (Twisdale and Vickery, 1992) showed that, when the mechanisms were separated, then the winds generated by thunderstorms at the stations that are located far from the coast are underestimated if the other mechanisms are not separated before the analysis. The use of Fisher-Tippett type I distributions is theoretically applicable to only one mechanism at a time. The use of a Fisher-Tippett type II distribution to simulate mixed mechanisms is merely pragmatism without a theoretical basis.
