Spatial and Temporal Distribution of Avalanche Problems in Western Canada: An Analysis of the Winters 2010-2016 (original) (raw)
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While the effect of large-scale climate patterns (e.g., El Niño-Southern Oscillation) on winter temperature and precipitation in Western Canada is relatively well understood, little is known regarding the link between climate and avalanche hazard. Previous studies have been hindered by the inconsistent or incomplete avalanche, weather, and snowfall observations. Using avalanche hazard assessments from Avalanche Canada and Parks Canada from the 2009/10 to 2016/17 winter seasons I examined the nature and variability of avalanche hazard and the relationship to large-scale climate patterns. I identify typical avalanche hazard situations and calculate their seasonal prevalence to develop a quantitative measure of the nature of local avalanche hazard conditions. I then use the prevalence values of typical hazard conditions to examine the relationship between climate oscillations and avalanche hazard. This study suggests a relationship between the climate patterns and avalanche hazard situations with a method that is more informative for avalanche risk management.
Snow avalanche hazard assessment and risk management in northern Quebec, eastern Canada
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In the northern environments of Quebec (eastern Canada), snow avalanche hazards have been ignored for a long time because no major incident was recorded before the tragedies of Blanc-Sablon (Lower North Shore of the St. Lawrence River) in 1995 and Kangiqsualujjuaq (Nunavik) in 1999. To enhance risk reduction at these sites, this research on process characteristics describes prone terrain, run-out distance and triggering factors, and prompted efforts (permanent and temporary measures) made to mitigate and prevent future snow avalanche tragedy from short, steep slopes. Considering the high vulnerability of these communities related to the growing population of Nunavik and the lack of knowledge of avalanches on the Lower North Shore, acceptable risk was based on the implementation of a snow avalanche forecasting and warning program over 3 years, the first one in eastern Canada. Community participation and the involvement of the municipal and provincial authorities have enabled the efficient operation of the program and accentuate the sensitivity and resilience of the populations to avalanche hazard and risk, as evidenced by the subsequent identification of avalanche sites by the communities themselves. These case studies demonstrate the importance of adequate and safe land planning, notably in the context of climate change, and particularly for isolated northern communities.
Avalanche Threats and Mitigation Measures in Canada
arc.lib.montana.edu
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A climatology of major avalanche winters in Western Canada
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A nearly continuous record of avalanches on the Canadian PaciJc Railway for the 70 yearsfrom 1910 is used to idenrify four major avalanche Winters (1919-20,1932-33, 1934-35 and 1971-72). The selection is based on the j?equency and mass of avalanche snow, and the length of rail line affected near Rogers Pass, British Columbia. Daily weather data are compiled for rhese Winters, and su$ace synoptic charts are examined for the mosr catastrophic avalanche events. Their climatology is furrher analysed by applying a weathertyping scheme and by constructing monthly sea-level pressure anomaly maps. More than one climatology is needed to explain these Winters and the daily sea-level map types are not very discriminating. Major avalanche Winters tend to be cold in December or January or bath. Some show large monthly anomalies in the average pressure distribution over the province. Large avalanches occur when there is a change in the atmospheric circulation, with a Pac$c fionral sysrem and warm sector replacing an Arctic high. These aspects of synoptic climatology are related to the mechanisms for producing big avalanches.
Verification of Canadian avalanche bulletins including spatial and temporal scale effects
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In the winters of 2004-05 and 2005-06, 235 local ratings of the current avalanche danger ("nowcasts") 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 regional bulletins are issued from three to seven times per week, and the forecast regions range from 100 km 2 to approximately 29,000 km 2 . After identifying an observation bias and filtering the data to 192 cases, the local nowcasts agreed with the regional danger rating in approximately 59% 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 nowcasts could be compared with danger ratings published zero, one or two days previously, allowing the effect of different lead times to be assessed. For the observed range of forecast areas and lead times, spatial scale effects were greater than temporal scale effects.
2018
Numerous large-scale atmosphere-ocean oscillations including El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), the Pacific North American Pattern (PNA) and the Artic Oscillation (AO) are known to substantially affect winter weather patterns in western Canada. Several studies have examined the effect of these oscillations on avalanche hazard using long-term avalanche activity records from highway avalanche safety programs. While these studies offer valuable insights, they do not offer a comprehensive perspective on the influence of these oscillations because the underlying data only represent the conditions at a few locations in western Canada where avalanches are tightly managed. We present a new approach for gaining insight into the relationship between atmosphere-ocean oscillations and avalanche hazard in western Canada that uses information published in public avalanche bulletins. Our approach converts hazard assessments recorded according to the concept...
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The paper presents interesting approach of combination of "avalanche climates" and the snow avalanche hazard characteristics based on extensive database of the catalogued actual snow avalanches in western Canada. Results of similar "comprehensive" studies, going a bit further, were reported in past (i.e. Miagkov S.M. Kanaev L.A. (Eds.) Geografiia lavin [Geography of avalanches], Moscow: Izdatel’stvo Moskovskogo universiteta, 1992. 331p.). Also, there are several classifications of the snow avalanches produced in Russia, including the "genetic classification" of V.V.Dzuba presented in the book cited above, where the types of avalanches were related to meteorology and stratigraphy of snow cover, definitely related to the conclusions in the presented manuscript. But it was pub-
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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 km 2 to approximately 30,000 km 2 . After identifying an observation bias and filtering the data to 192 cases, the local nowcasts 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 nowcasts 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 potentia...
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