Naturally triggered persistent deep slab avalanches in western Canada Part I: avalanche characteristics and weather trends from weather stations

Conlan, Michael; Jamieson, Bruce

doi:10.1017/jog.2016.1

Cited by 4 publications

(3 citation statements)

References 38 publications

(56 reference statements)

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“…If we use the direction and velocity information of 07h, 14h and 19h wind data we are able to compute the mean wind load according to Conlan and Jamieson (2016). However, there are only noteworthy results for St. Anton am Arlberg: 7h (effect: 7.564, p-value: 0.0), 14h (4.351, 0.0) 19h( 5.518, 0).…”

Section: Resultsmentioning

confidence: 99%

Effects of Precipitation, Temperature and Wind in Alpine Areas on Backcountry Avalanche Accidents Reported in the Western Part of Austria within 1987-2009

Pfeifer

Höller

2021

Preprint

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In this article, we are going to investigate the effects of snow, rain, temperature and wind on the number of backcountry and off-piste avalanche accidents. The data base of our survey is restricted on the western part of Austria (federal states Tyrol and Vorarlberg) within the winter periods 1987/88--2008/09. We are able to stratify the daily data for municipalities in Tyrol and Vorarlberg. Employing spatial kriging and hurdle models, we found a positive significant effect of the snow water equivalent measurement on avalanche accident counts (if we consider the running average over the past 3 days). The variables rain and temperature 1800 meter above sea level showed negative effects on the number of accident counts. In the case of the variable wind - ERA5 global reanalysis data turned out not to be reliable -- we had a focus on the 3 avalanche accident hot spots of Austria St. Anton am Arlberg, Lech and Sölden observing wind data of the weather stations Galzig, Warth and Obergurgl. At least in the case of St. Anton and Lech, we found significant positive effects (daily velocity totals and west wind component) on the number of avalanche counts. Calculating the daily mean wind load showed a positive effect only in the case of St. Anton am Arlberg.Finally, we tried to find conclusions in connection with `avalanche problems' such as used by several avalanche information services only finding (beside `new snow') some evidence for a `spring scenario'.

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Section: Resultsmentioning

confidence: 99%

Effects of Precipitation, Temperature and Wind in Alpine Areas on Backcountry Avalanche Accidents Reported in the Western Part of Austria within 1987-2009

Pfeifer

Höller

2021

Preprint

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“…Recent research has studied meteorological thresholds prior to the onset of avalanche activity, highlighting the importance of precipitation totals, daily maximum temperatures, and rain events in time periods ranging from 24 h to 7 d prior to onset of activity (e.g., Marienthal et al, 2015;Conlan et al, 2014;Savage, 2006). Conlan and Jamieson (2017) used survey data from avalanche professionals to develop a decision-making tool to aid in forecasting deep slab avalanches. Their tool uses snowpack properties, weather history, and recent avalanche activity to correctly predict deep slab avalanche activity for 77 out of 103 d -roughly 75 % of the days used in their study.…”

Section: Introductionmentioning

confidence: 99%

Synoptic atmospheric circulation patterns associated with deep persistent slab avalanches in the western United States

Schauer

Hendrikx

Birkeland

et al. 2021

Nat. Hazards Earth Syst. Sci.

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Abstract. Deep persistent slab avalanches are capable of destroying infrastructure and are usually unsurvivable for those who are caught. Formation of a snowpack conducive to deep persistent slab avalanches is typically driven by meteorological conditions occurring in the beginning weeks to months of the winter season, and yet the avalanche event may not occur for several weeks to months later. While predicting the exact timing of the release of deep persistent slab avalanches is difficult, onset of avalanche activity is commonly preceded by rapid warming, heavy precipitation, or high winds. This work investigates the synoptic drivers of deep persistent slab avalanches at three sites in the western USA with long records: Bridger Bowl, Montana; Jackson, Wyoming; and Mammoth Mountain, California. We use self-organizing maps to generate 20 synoptic types that summarize 5899 daily 500 mbar geopotential height maps for the winters (November–March) of 1979/80–2017/18. For each of the three locations, we identify major and minor deep persistent slab avalanche seasons and analyze the number of days represented by each synoptic type during the beginning (November–January) of the major and minor seasons. We also examine the number of days assigned to each synoptic type during the 72 h preceding deep persistent slab avalanche activity for both dry and wet slab events. Each of the three sites exhibits a unique distribution of the number of days assigned to each synoptic type during November–January of major and minor seasons and for the 72 h period preceding deep persistent slab avalanche activity. This work identifies the synoptic-scale atmospheric circulation patterns contributing to deep persistent slab instabilities and the patterns that commonly precede deep persistent slab avalanche activity. By identifying these patterns, we provide an improved understanding of deep persistent slab avalanches and an additional tool to anticipate the timing of these difficult-to-predict events.

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“…The goals of our study were to determine the practical use of weather station and weather model data for avalanche forecasting in western Canada and to determine typical weather parameter values prior to the release of persistent deep slab avalanches. Part I of this two-part study first examined weather station data to determine typical weather parameter values observed prior to the natural release of persistent deep slab avalanches (Conlan and Jamieson, 2016). Median precipitation amounts were 15 and 38 cm for 24 h and 3 d cumulative amounts, respectively.…”

Section: Introductionmentioning

confidence: 99%

Naturally triggered persistent deep slab avalanches in western Canada Part II: weather trends from model forecasts

Conlan

Jamieson

2016

J. Glaciol.

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ABSTRACT. For 175 difficult-to-forecast persistent deep slab avalanches, weather data were obtained from Global Environmental Multiscale (GEM) models produced by Environment Canada. The focus was to determine critical parameters and thresholds for avalanche forecasting from GEM and compare them with weather station data analyzed in Part I (Conlan and Jamieson, this issue). The high-resolution GEM-limited-area model (2.5 km resolution) forecasted higher median precipitation amounts than both the lower-resolution GEM15 (15 km resolution) and weather stations within a small dataset. Air temperatures were lower for both weather models compared with the weather station data, likely because of elevation differences. A multivariate classification tree created with GEM15 data correctly classified 29 of 36 avalanches by their primary cause-of-release, using a primary split of modelled solar warming of 5.9°C, 10 cm into the snowpack. For all 175 avalanches, GEM15 forecasted significantly less precipitation than observed at the weather stations, particularly with multi-day cumulative amounts. The majority of GEM15 surface wind speeds were between 0 and 10 km h , producing negligible wind loading amounts. The parameter values may be helpful for predicting future persistent deep slab avalanches. However, GEM output is not always representative of field conditions and should be used in conjunction with other sources.

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Naturally triggered persistent deep slab avalanches in western Canada Part I: avalanche characteristics and weather trends from weather stations

Cited by 4 publications

References 38 publications

Effects of Precipitation, Temperature and Wind in Alpine Areas on Backcountry Avalanche Accidents Reported in the Western Part of Austria within 1987-2009

Effects of Precipitation, Temperature and Wind in Alpine Areas on Backcountry Avalanche Accidents Reported in the Western Part of Austria within 1987-2009

Synoptic atmospheric circulation patterns associated with deep persistent slab avalanches in the western United States

Naturally triggered persistent deep slab avalanches in western Canada Part II: weather trends from model forecasts

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