Frequency of weather patterns in the European Alps

Schuepp (1) has classified daily weather patterns in the European Alps in several types, mainly 'convective' (dominated by topographically-induced mesoscale flows, and thunderstorms), 'advective' (essentially frontal), and ‘high-pressure’. The classification depends on four features: the surface pattern of pressure, the direction of the geostrophic winds over the region, the upper level wind speed and direction, and the 1000-500 hPa thickness, which is a measure of air temperature.

The relative frequency of these weather systems appears to have changed a little over the last half-century (1). Convective kinds of weather have become more common, with fewer advective weather patterns, especially in winter, when they are most common. It is also observed that the occurrence of ‘high-pressure’ patterns correlates strongly with the North Atlantic Oscillation.

(1) Stefanicki, G., P. Talkner and R.O. Weber 1998. Frequency changes of weather types in the Alpine region since 1945. Theor. Appl. Climatol., 60, 47-61.