Verification is a difficult yet important part to improve avalanche forecasting. During winter 1996/97 verification activities took place for the area of Davos (approx. 200 km² ). At ISSW '96 a prototype GIS-application LAWIPROG was presented to visualise the verbal avalanche bulletin of the Swiss Federal Institute for Snow and Avalanche Research (Davos). For evaluation of the verification LAWIPROG was used.
All observed avalanches in the test area were recorded and classified. Moreover, mountain guides, ski patrol teams and private mountaineers were asked to report their observations concerning the snow pack and avalanche situation with a standardised questionnaire. The observed avalanches were introduced to the GIS-database and analysed for spatial characteristics. All this information was combined in order to estimate the "real" avalanche danger in the form of a subjective verification. LAWIPROG was enhanced with functionalities to visualise the difference between the forecasted bulletin and the effective situation verified in situ. For each bulletin a map was calculated which shows where the bulletin is either accurate, too high or too low. Additionally, the difference between bulletin and verification can be visualised using a circle diagram where variations in exposition and altitude are emphasised. Concerning only the overall hazard level, in the test area 88% of the days the bulletin and the verification matched. Tendencies in which aspects and at what altitudes the bulletin was either too low or too high can be recognised.