Item: Ten years experience with the five level avalanche danger scale and the gis database in switzerland
Title: Ten years experience with the five level avalanche danger scale and the gis database in switzerland
Proceedings: Proceedings of the 2004 International Snow Science Workshop, Jackson Hole, Wyoming
Authors: Andreas Stoffel and Roland Meister, Swiss Federal Institute for Snow and Avalanche Research SLF Switzerland
Abstract: In 1993 the European avalanche warning services agreed on a standardized, five level avalanche danger scale. Since then, this danger scale has been in daily use in Switzerland. The organization of the warning service and the experience with this avalanche danger scale over a period of 10 years from winter 1993/94 to winter 2002/03 are described. The Swiss Alps are subdivided into 117 spatial units, covering a total area of 26’114 km2. These spatial units were formed by dividing the Swiss first order administrative boundaries with the basic meteorological and climatologic regions of the Swiss Alps. In regard to dry slab avalanches, a 10-year mean score of 2.12 with respect to the five levels (1-5) was found, with no significant trend and varying frequency distributions from one year to another. The regions with the highest mean danger scores in the 10-year period are the northern Gotthard massif (central Switzerland) and the Great Saint Bernard massif (close to the French border, near Mont Blanc). Low mean danger scores are found in the lowlands of southern Switzerland. In the last winters, forecasters tended to apply higher altitudes but wider aspect sectors for the especially exposed terrain parts. These results may help to improve the forecasting methods and danger communication as started in Colorado’s avalanche danger rose.
Keywords: avalanche forecasting, avalanche danger scale, swiss alps, mountain climate
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