Snow avalanches are a common hazard in many mountainous environments. As such, it is often necessary to be able to predict these events. In this study detailed analysis of weather parameters in western Norway has established common triggering factors for avalanches in Grasdalen. Two large sets of weather data have been used. A number of wind drift factors have been derived, as several authors consider these to be important. Statistical procedures were applied, including cumulative probability plots and classification trees. The latter highlighted the most important weather parameters used to...