Technology - Storm modelling - AIR seminar stresses need to model European windstorms.

(From Reinsurance)

European extratropical cyclones are a unique phenomenon that require a great deal of modelling to predict their possible paths, according to risk modelling firm AIR.

Speaking at a seminar on improving detailed loss estimates through the physical modelling of European storms at the Lloyd's Library in February, Dr Peter Dailey, manager of atmospheric sciences at AIR, stressed the need for (re)insurers to understand the complex nature and unpredictable consequences of these events.

Dr Dailey said past windstorms such as Lothar and Martin could have been much worse if they had deviated from their paths by just a few miles.

He said a small shift in the position of the jet stream would have moved Lothar over cities such as Zurich and Munich, which would have led to a 25% increase in the amount of damage. As it was, Lothar contributed a substantial part to the EUR7.7bn insurance bill for the damage it and Martin inflicted on Europe.

According to Dr Dailey there are a small number of key conditions that can affect the intensity of a storm, including the location and strength of the jet stream, the amount of moisture in the air and the strength of any turbulence and vertical motion of air masses.

Slight differences in these conditions can send an extratropical cyclone off in a different direction than predicted, as well as making it stronger or weaker than before.