Item: Spatial and time scale effects in canadian avalanche bulletins
Title: Spatial and time scale effects in canadian avalanche bulletins
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: Bruce Jamieson, Cam Campbell, Alan Jones, Dept. of Civil Engineering, University of Calgary, Calgary, Alberta, Dept. of Geology and Geophysics, University of Calgary, Calgary, Alberta Revelstoke, BC
Abstract: In the winters of 2004-05 and 2005-06, 235 local “nowcasts” of the avalanche danger at and below treeline in the Coast, Columbia and Rocky Mountains of western Canada were compared with the danger rating from the public avalanche bulletin for the region including the nowcast site. These bulletins are issued from three to seven times per week, and the forecast regions range from 100 km2 to approximately 30,000 km2. After identifying an observation bias and filtering the data to 192 cases, the local newcasts agreed with the regional danger rating in approximately 57% to 64% of the cases in the Coast, Columbia and Rocky Mountains. The agreement rate was higher for small forecast regions than for larger regions. Many of the newcasts could be compared with danger ratings published zero, one or two days previously. This allowed the effect of different lead times to be assessed. It appears that the danger rating for the larger regions with infrequent bulletins has the potential to be improved more by reducing the size of the forecast regions than by increasing the frequency of forecasts from three times per week to five or seven times per week.
Keywords: avalanche forecasting, scale issue, spatial scale, temporal scale, avalanche danger
Digital Abstract Not Available