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Information about changes in snow avalanche activity due to ongoing climate change is necessary for reasonable reliable protection in mountain regions especially in areas with developed economic and recreational activities. The changes in the maximum snow depth at the meteorological site during the winter period, the number of days with snow cover, the number of avalanches per year, the duration of the avalanche period, the number of avalanche periods, the maximum and total volume of avalanches were considered for two regions located in the spurs of the Chatkal and the Kuraminsky Ridges, the Western Tien-Shan. The dynamics of these characteristics was compared with the indicators of the average monthly air temperature and the precipitation sum for the entire observation period since 1980-s and for some individual periods in which multidirectional changes in some indicators were identified. An assessment of current changes was compared to the 30-year WMO climate normal for 1981–2010. The previously identified indicative climate characteristics which determine the regime of snow accumulation and avalanching in these areas were refined. The most important indicators to assess the maximum values of avalanche characteristics are the average air temperature in January and the temperature and precipitation sums from November to March / April. Changes in meteorological conditions in April play an important role in assessing changes in the duration of the avalanche period. The resulting dependences can serve as a basis for estimating avalanche indicators for the future taking into account possible climate change scenarios., Информация об изменении снеголавинной активности в связи с происходящими климатическими изменениями и оценке лавинного режима на перспективу необходима для обоснованной надежной защиты в лавиноопасных зонах, особенно в районах с развитой хозяйственной и рекреационной деятельностью. Для двух районов, расположенных в отрогах Чаткальского и Кураминского хребтов (Западный Тянь-Шань), рассмотрено изменение таких важных показателей снеголавинного режима, как максимальная высота снега на метеорологической площадке за зимний период, число дней со снежным покровом, количество лавин за год, продолжительность лавиноопасного периода, число лавиноопасных периодов, максимальный и суммарный объем лавин. Сравнение динамики этих показателей с показателями среднемесячной температуры воздуха и суммой осадков проводилось как за весь период наблюдений, так и за отдельные периоды. Выявлены периоды разнонаправленных изменений некоторых показателей и проведена оценка текущих изменений по сравнению с 30-летней климатической нормой всемирной метеорологической организацией за период с 1981 по 2010 год. Уточнены выявленные ранее индикационные показатели климата, определяющие режим снегонакопления и лавин в данных районах. Для оценки максимальных величин снеголавинных характеристик наиболее важными являются среднемесячная температура воздуха в январе и сумма температур и осадков с ноября по март-апрель. В оценке изменений продолжительности лавиноопасного периода большую роль играют изменения метеорологических условий в апреле. Полученные зависимости могут служить основой для расчета снеголавинных показателей на перспективу с учетом возможных сценариев изменения климата. Предложен подход к картографированию максимальной высоты снега в различных климатических условиях. В качестве примера, приведена оценка изменения снеголавинных показателей в районах исследования при повышении суммы температур воздуха с ноября по март на 1°С и увеличении суммы осадков с ноября по март на 10%.

At the moment, the Khibiny mountains are one of the most dynamically developing regions in the Arctic. Over the past decade, the number of tourists visiting the area of Kirovsk has increased 10 times. Such types of winter tourism as skiing and cross-country skiing are developed here. Khibiny mountains is one of the centers for the development of extreme sports in Russia. Avalanches come down here every year, which lead to human casualties. Catastrophic avalanche events have been occurring in the Khibiny mountains almost every year since the early 2000s due to an increase in the tourists and the development of new tourist destinations. Over the past two decades, the proportion of victims of avalanches among free ride has increased, and after 2015 a new category of avalanche victims has appeared – snowmobile drivers. Since 2000, about 60 people have been involved in avalanches in Khibiny mountains and over 80% of them were tourists. An assessment of the social avalanche risk was carried out in Khibiny mountains in 2008 and 2019 using a methodology based on a combination of avalanche activity parameters and socio-economic parameters that characterize human vulnerability to avalanches in space and time. Estimated avalanche risk indicators in the Khibiny have increased 7 times over the past decade – from 23 to 159. High avalanche risk values are typical for areas where skiing is developed. Avalanche areas where off-piste skiing takes place are also characterized by increased risk values., На данный момент Хибины один из самых динамично развивающихся регионов в Арктике. За последнее десятилетие количество туристов, посещающих район города Кировска, выросло в десять раз. Здесь традиционно развиты такие виды зимнего туризма, как горнолыжный спорт и беговые лыжи. Хибины также являются одним из центров развития экстремальных видов спорта в нашей стране. Несмотря на то, что горы имеют небольшую площадь и высоту, здесь ежегодно сходят лавины, которые приводят к человеческим жертвам. Катастрофические события, связанные с лавинами, случаются в Хибинах практически ежегодно, начиная с начала 2000-х годов за счет увеличения туристического потока и развития новых видов активного отдыха. В последние два десятилетия повысилась доля жертв от лавин среди любителей фрирайда, а после 2015 года появилась новая категория пострадавших от лавин – водители снегоходов. С 2000 года в Хибинах в лавины попали свыше 60 человек и свыше 80% из них составили туристы. Оценка социального лавинного риска была проведена в Хибинах в 2008 и 2019 годах с использованием методики, основанной на сочетании параметров лавинной активности и социально-экономических параметров, характеризующих уязвимость человека по отношению к лавинам в пространстве и во времени. Расчетные показатели лавинного риска в Хибинах выросли в семь раз за последнее десятилетие – с 23 до 159. Высокие значения лавинного риска характерны для территорий развития горнолыжного спорта. Практически все существующие горнолыжные комплексы Хибин могут подвергаться воздействию лавин. Участки лавиносборов, в которых происходит внетрассовое катание, также характеризуются повышенными значениями риска. Динамика лавинного риска и увеличение количества пострадавших от лавин туристов говорят о том, что обеспечение лавинной безопасности должно быть в приоритете при дальнейшем развитии региона.

На данный момент Хибины один из самых динамично развивающихся регионов в Арктике. За последнее десятилетие количество туристов, посещающих район города Кировска, выросло в десять раз. Здесь традиционно развиты такие виды зимнего туризма, как горнолыжный спорт и беговые лыжи. Хибины также являются одним из центров развития экстремальных видов спорта в нашей стране. Несмотря на то, что горы имеют небольшую площадь и высоту, здесь ежегодно сходят лавины, которые приводят к человеческим жертвам. Катастрофические события, связанные с лавинами, случаются в Хибинах практически ежегодно, начиная с начала 2000-х годов за счет увеличения туристического потока и развития новых видов активного отдыха. В последние два десятилетия повысилась доля жертв от лавин среди любителей фрирайда, а после 2015 года появилась новая категория пострадавших от лавин – водители снегоходов. С 2000 года в Хибинах в лавины попали свыше 60 человек и свыше 80% из них составили туристы. Оценка социального лавинного риска была проведена в Хибинах в 2008 и 2019 годах с использованием методики, основанной на сочетании параметров лавинной активности и социально-экономических параметров, характеризующих уязвимость человека по отношению к лавинам в пространстве и во времени. Расчетные показатели лавинного риска в Хибинах выросли в семь раз за последнее десятилетие – с 23 до 159. Высокие значения лавинного риска характерны для территорий развития горнолыжного спорта. Практически все существующие горнолыжные комплексы Хибин могут подвергаться воздействию лавин. Участки лавиносборов, в которых происходит внетрассовое катание, также характеризуются повышенными значениями риска. Динамика лавинного риска и увеличение количества пострадавших от лавин туристов говорят о том, что обеспечение лавинной безопасности должно быть в приоритете при дальнейшем развитии региона., At the moment, the Khibiny mountains are one of the most dynamically developing regions in the Arctic. Over the past decade, the number of tourists visiting the area of Kirovsk has increased 10 times. Such types of winter tourism as skiing and cross-country skiing are developed here. Khibiny mountains is one of the centers for the development of extreme sports in Russia. Avalanches come down here every year, which lead to human casualties. Catastrophic avalanche events have been occurring in the Khibiny mountains almost every year since the early 2000s due to an increase in the tourists and the development of new tourist destinations. Over the past two decades, the proportion of victims of avalanches among free ride has increased, and after 2015 a new category of avalanche victims has appeared – snowmobile drivers. Since 2000, about 60 people have been involved in avalanches in Khibiny mountains and over 80% of them were tourists. An assessment of the social avalanche risk was carried out in Khibiny mountains in 2008 and 2019 using a methodology based on a combination of avalanche activity parameters and socio-economic parameters that characterize human vulnerability to avalanches in space and time. Estimated avalanche risk indicators in the Khibiny have increased 7 times over the past decade – from 23 to 159. High avalanche risk values are typical for areas where skiing is developed. Avalanche areas where off-piste skiing takes place are also characterized by increased risk values., Гидросфера. Опасные процессы и явления, Выпуск 3 2023, Pages 276-287

Snow avalanches pose a hazard in alpine environments. There is a need to improve monitoring capabilities in order to reliably detect and locate avalanche activity, which will help to validate avalanche hazard assessments. Recent work has demonstrated the utility of infrasound as it can provide continuous monitoring and broad geographic coverage. Here, we present the first use of infrasound to monitor snow avalanche activity in a maritime climate along the Milford Road in Fiordland, New Zealand (Aotearoa). Size 4 (or larger) plunging avalanches frequently occur along the Milford Road, which travels through a glacial-carved valley with steep cliffs (slope angles can exceed 50 $$^\circ$$ ) that are over 1000 m tall. We deployed two infrasound arrays on the eastern side of the Homer Tunnel and recorded triggered and natural avalanches during our month-long field campaign. We use array processing to identify avalanche signals, calculate back-azimuths, and triangulate source locations. Source locations are well constrained for avalanches that are in-network but are worse for avalanches that occur out-of-network, likely due to topographic scattering of acoustic waves from the steep valley walls. The infrasound amplitudes are substantially larger than previously recorded at other locations with a maximum peak-to-peak amplitude of 37 Pa detected for a large triggered avalanche, which reflects the unique dynamics of the avalanches along the Milford Road. This study demonstrates the utility of infrasound for snow avalanche monitoring in maritime climates and showcases an efficient processing workflow that could be easily operationalized.

Contains the code, data and analysis results for Haegeli, P., Shandro, B., and Mair, P.: Using avalanche problems to examine the effect of large-scale atmosphere-ocean oscillations on avalanche hazard in western Canada, Submitted to The Cryosphere on May 30, 2020.

Contains the code, data and analysis results for Fisher, K., Haegeli, P., and Mair, P.: Impact of information presentation on interpretability of spatial hazard information: Lessons from a study in avalanche safety, Accepted for publication in Natural Hazards and Earth System Sciences on Sept. 29, 2021.

Contains the code, data and analysis results for Fisher, K. C., Haegeli, P., & Mair, P. (2022). Travel and terrain advice statements in public avalanche bulletins: a quantitative analysis of who uses this information, what makes it useful, and how it can be improved for users. Nat. Hazards Earth Syst. Sci., 22(6), 1973-2000. doi:10.5194/nhess-22-1973-2022.

This paper presents the reconstruction results of catastrophic avalanche characteristics. The avalanche occurred on the slope of the Gora Otdelnaya ski resort on January 9, 2021 (Norilsk). It had a peak pressure of 0.266 MPa and led to the destruction of a suburban settlement, covering an area of about 0.9 ha. Six people got caught in the avalanch, of whom three were killed. The virtual and calculated boundaries of the maximum avalanche run-out distance are given. The causes of the catastrophe are also under investigation. An avalanche hazard assessment methodology for the Russian Arctic region and other poorly studied areas with no long-term avalanche observations is suggested.

Snow avalanches are a common natural hazard in many countries with seasonally snow-covered mountains. The avalanche hazard varies with snow avalanche type in different snow climate regions and at different times. The ability to understand the characteristics of avalanche activity and hazards of different snow avalanche types is a prerequisite for improving avalanche disaster management in the mid-altitude region of the Central Tianshan Mountains. In this study, we collected data related to avalanche, snowpack, and meteorology during four snow seasons (from 2015 to 2019), and analysed the characteristics and hazards of different types of avalanches. The snow climate of the mid-altitude region of the Central Tianshan Mountains was examined using a snow climate classification scheme, and the results showed that the mountain range has a continental snow climate. To quantify the hazards of different types of avalanches and describe their situation over time in the continental snow climate region, this study used the avalanche hazard degree to assess the hazards of four types of avalanches, i.e., full-depth dry snow avalanches, full-depth wet snow avalanches, surface-layer dry snow avalanches, and surface-layer wet snow avalanches. The results indicated that surface-layer dry snow avalanches were characterized by large sizes and high release frequencies, which made them having the highest avalanche hazard degree in the Central Tianshan Mountains with a continental snow climate. The overall avalanche hazard showed a single peak pattern over time during the snow season, and the greatest hazard occurred in the second half of February when the snowpack was deep and the temperature increased. This study can help the disaster and emergency management departments rationally arrange avalanche relief resources and develop avalanche prevention strategies.

Glacial avalanche hazard poses threat to human lives and damage settlements / infrastructures in alpine glaciers mountainous regions. A gigantic ice plus rock avalanche destroyed Gyari military camp in Siachen sector on April 2012 and buried 139 personals. The study focuses on geospatial analysis and simulation of Shishper glacial avalanche of Hunza basin. To simulate the potential glacial avalanche hazard to Hassan Abad settlements, an empirical process based Glacier Avalanche Model; Rapid Access Mass Movement Simulation (RAMMS) is utilized. The model encompasses avalanche release area and height for the execution of simulation. The model output of Shishper glacial avalanche resulted; a max pressure of 450 Kpa, max velocity of 40 m/s, and the max flow height of 80m, while the resulted surge extent output was 2500m. The potential hazardous Shishper glacial avalanche remains a continuous hazard to Hassan Abad of Hunza valley including Karakoram Highway and Frontier Works Organization (FWO) camp. The study has resulted in identifying the Upper Indus Bain (UIB) being more prone to glacial avalanche hazards because of host factors in general and the anthropogenic factor in particular.

This work introduces the S2M (SAFRAN - SURFEX/ISBA-Crocus - MEPRA) meteorological and snow cover reanalysis in the French Alps, Pyrenees and Corsica, spanning the time period from 1958 to 2020. The simulations are made over elementary areas, referred to as massifs, designed to represent the main drivers of the spatial variability observed in mountain ranges (elevation, slope and aspect). The meteorological reanalysis is performed by the SAFRAN system, which combines information from numerical weather prediction models (ERA-40 reanalysis from 1958 to 2002, ARPEGE from 2002 to 2020) and the best possible set of available in-situ meteorological observations. SAFRAN outputs are used to drive the Crocus detailed snow cover model, which is part of the land surface scheme SURFEX/ISBA. This model chain provides simulations of the evolution of the snow cover, underlying ground, and the associated avalanche hazard using the MEPRA model. This contribution describes and discusses the main climatological characteristics (climatology, variability and trends), and the main limitations of this dataset. We provide a short overview of the scientific applications using this reanalysis in various scientific fields related to meteorological conditions and the snow cover in mountain areas. An evaluation of the skill of S2M is also displayed, in particular through comparison to 665 independent in-situ snow depth observations. Further, we describe the technical handling of this open access data set, available at this address: http://dx.doi.org/10.25326/37#v2020.2. Scientific publications using this dataset must mention in the acknowledgments: "The S2M data are provided by Météo-France - CNRS, CNRM Centre d’Etudes de la Neige, through AERIS" and refer to it as Vernay et al. (2020).

While guides in mechanized skiing operations use a well-established terrain selection process to limit their exposure to avalanche hazard and keep the residual risk at an acceptable level, the relationship between the open/closed status of runs and environmental factors is complex and has so far only received limited attention from research. Using a large dataset of over 25 000 operational run list codes from a mechanized skiing operation, we applied a general linear mixed-effect model to explore the relationship between skiing terrain that is deemed appropriate for guiding (i.e., status open) and avalanche hazard conditions. Our results show that the magnitude of the effect of avalanche hazard on run list codes depends on the type of terrain that is being assessed by the guiding team. Ski runs in severe alpine terrain with steep lines through large avalanche slopes are much more susceptible to increases in avalanche hazard than less severe terrain. However, our results also highlight the strong effects of recent skiing on the run coding and thus the importance of prior first-hand experience. Expressing these relationships numerically provides an important step towards the development of meaningful decision aids, which can assist commercial operations to manage their avalanche risk more effectively and efficiently.

The climate change during cold seasons of 1995–2017 in the Central Caucasus is estimated, and its influence on the avalanche regime is shown. Data on the avalanche releases in the Central Caucasus for the period 1968– 2017 together with observations of high-altitude meteorological stations were used for the analysis. The paper presents estimates of snowiness of the winters and their frequency of occurrence in the area under investigation. The winter snowiness was noted to decrease since the beginning of the 2000s. The last decade of the period was not snowy, especially its series of six winters having very small amounts of snow. It is shown that in the second half of the XX century the heaviest snowfalls took place mostly in Januaries, and they were followed by releases of avalanches with the volumes exceeding 1 million cubic metres. In the early 2000‑ies, intensive January snowfalls were observed later, i.e. during the winter-spring period. In the warmer months March and April, the destructive potential of avalanches was noticeably smaller. In the present time, the warming and decrease of winter snowiness resulted in significant diminution of the avalanche hazard in the region. At the same time, on the background of general warming the certain increase in inter-seasonal variability of air temperature was noted. These changes may be compared to the warming of 1910–1945 when during its warmest phase the Europe suffered with one of the harshest winters in 1941/42. The swing of the «temperature pendulum» indicates that a harsh winter with heavy snowfalls and avalanches with catastrophic consequences may occur on the background of winters with mild and moderate avalanche danger. This is one of probable scenarios in the development of avalanche activity in the Greater Caucasus in the context of the current climate change.

Avalanches cause the highest number of fatalities in the Alps, threatening many areas and facilities, as well as transport and communications infrastructure. An integral part of avalanche protection is risk communication and warning, which is within the domain of the avalanche service of the Slovenian Environmental Agency. As part of the ‘Crossrisk Project’, the ZRC SAZU Anton Melik Geographical Institute has prepared a ‘Snow Field Manual’ which will allow for the standardised collection of field data on snow, snow cover and avalanches. This data forms the basis for determining the current avalanche hazard level. The ‘Snow Card’ supplement, which is an integral part of the manual, contains a condensed view of the most important contents and also includes two forms (there are a total of 14 forms in the manual) for entering the snow cover cross-section data. It also includes instructions for preparing and performing cross-sections of snow cover and avalanche tests. All information is provided along with a clear explanation key. Finally, a description of typical avalanche problems and types of avalanche hazards follows. The full applicability of the Snow Field Manual and the Snow Card is achieved by entering the digital data of the cross-section and the avalanche test into the appropriate web application.

The avalanche hazard is a critical task for the regional services in the Alpine region. For this reason, the characteristics of surface snow are continuously monitored in terms of micro-physics and metamorphism. The spatial distribution of the different types of snow covers (fresh snow, drift snow, melted snow, surface hoar, rain crusts, wet snow, dry snow) are used in the models aimed to forecast the avalanche hazard.Satellite data are very important for routinely monitoring the snow cover and data provided by the Moderate Resolution Imaging Spectroradiometer (MODIS), onboard on the Terra and Aqua platforms, are an useful source of information for a modern avalanche assessment service.More than one hundred MODIS images were processed, in the 2013-2020 period, for 2 areas located in the Dolomites, between Marmolada and Pale di San Martino groups (Veneto Region, Italy). The two training sites were used for the definition of a workflow useful for discriminating different types of snow surface. The defined workflow, based on the average radiometric values of bands 4, 5 and 6, were applied on the reflectances derived by the daily product MOD02HKM, with a spatial resolution of 500m. While band 4 and 5 (respectively visible radiation at 550nm and short-wave infrared at 1240nm) support the discrimination of different snow surfaces, the band 6 (short-wave infrared at 1630nm) is linked mainly to the presence of dry or wet snow on the surface.The proposed workflow provided classification maps that were validated using observations recorded at the meteorological stations located in the test areas and by field surveys carried out by snow scientists. These results support the availability of a reliable tool based on remotely-sensed data, evidenced by the good agreement with field observations, which can be an optimal input for avalanche forecasting.

Land cover and particularly forests have significant impact on snow avalanche initiation and propagation. Mountain forests can prevent avalanche initiation by stabilizing the snow in release areas, and potentially decelerate an avalanche, thus reducing runout distances. Interaction between forests and avalanches is recognized in avalanche modelling mostly by increasing friction parameters. For instance, the dry –Coulomb friction μ of the Voellmy friction law is thought to summarize snow properties, whereas the velocity-dependent friction ξ aims at representing the roughness of the path potentially related to land cover properties. In this work, we hypothesize on the temporal variability of both friction factors, inherited from their dependability on land cover, particularly the forest fraction, namely the aerial percentage of the terrain covered by forests within the extension of the avalanche path. Specifically, we show how the evolution of the forest fraction within the avalanche path affects the return period of runout distances and further dynamical characteristics of simulated avalanches. First, a Bayesian statistical-dynamical model is used to model avalanche frequency and magnitude on the selected path. The two processes are independently modelled, and the joint posterior distribution is estimated using a sequential Metropolis-Hastings algorithm. The forest-avalanche interaction is represented by increasing the total basal friction within the Voellmy friction law (TBF). Accordingly, to increase TBF, the velocity-dependent friction (turbulent friction) ξ is gradually decreased, whereas the dry –Coulomb friction μ is increased. To that end, ξ is assumed to be exponentially decaying with the forest fraction and is modelled as such. The dry –Coulomb friction μ is assumed to be normally distributed with parameters characterizing its dependency on the release abscissa, mean release depth and the forest fraction. Then, the return period for runout distances and the whole distribution of velocities, flow depths and pressures corresponding to any return periods is computed for different forest fractions representing the true forest evolution within the studied path. Results for a typical avalanche path of the French Alps notably show that, logically, the larger the forest fraction, the higher the return period, but only for runout distances exceeding a given threshold. Future work will include the explicit calibration of the forest cover dependency within the statistical-dynamical approach.

The goal of our research is to forecast the possible avalanches in the zones of active deforestation, especially situated close to the infrastructure objects and settlements.Despite the fact, that in Ukrainian Carpathians snow avalanches were observed by the Ukrainian Hydrometeorological Service, some recent events showed us, that it does not fulfill the current situation. The observations are regularly held in alpine and subalpine zones (>1300m. a.s.l.) of mountain ranges, in the same time territories with lower altitudes were not studied.Due to the active deforestation of the region in recent years, it appeared in new territories with conditions suitable for the appearance of avalanches. Because deforestation is mainly held on territories with lower altitudes, which are often densely settled, it makes such avalanches hazardous for the infrastructure and settlements. One of such avalanches occurred on the slope near village Kruhlyi (Rakhiv District, Zakarpatska oblast') in February 2019, that caused blocking of the international highway with 300 m3 of ice and snow. The avalanche occurred on the deforested area with altitudes between 400 and 480 m a.s.l., inclination around 28⁰ and 150m long. This event changes our vision in avalanche expectancy in the Carpathian Mountains to much lower altitudes. Research is currently being held based on data about deforestation and detecting areas with suitable avalanche properties.This research was supported by the project “Snow-avalanche activity from Romanian and Ukrainian Eastern Carpathians”, funded by AUF and IFA Romania.

The article is a review of mathematical models of snow avalanches that have been proposed since the middle of the 20th century and are still in use. The main attention is paid to the work of researchers from the Soviet Union and Russia, since many of their works were published only in Russian and are not widely available. Mathematical models of various levels of complexity for avalanches of various types&mdash, from dense to powder-snow avalanches&mdash, are discussed. Analytical solutions including formulas for the avalanche front speed are described. The results of simulations of the movement of avalanches are given that were used to create avalanche hazard maps. The last part of the article is devoted to constructing models of a new type, in which avalanches are considered as laminar or turbulent flows of non-Newtonian fluids, using the full (not depth-averaged) equations of continuum mechanics. The results of a numerical study of the effect of non-Newtonian rheology and mass entrainment on the avalanche dynamics are presented.

Introduction Carrying standard safety gear (beacon, probe, and shovel), planning a route of descent, and recreating with companions can help to mitigate the risk of injury or death resulting from avalanches in the backcountry. The goal of this study was to identify factors associated with performance of these safety practices. Methods A convenience sample of backcountry skiers and snowboarders was surveyed in 2016 at the backcountry gates of Jackson Hole Mountain Resort. Each participant was surveyed on characteristics including skill level, sex, age, prior avalanche education, and residency in the Jackson Hole area. Safety practices were also measured against avalanche hazard forecasts. Correlations were assessed using Fisher's exact testing. Results A total of 334 participants were surveyed. Factors associated with carrying avalanche safety gear included higher expertise, being a resident of the Jackson Hole area, and prior avalanche education. Factors associated with having a planned route of descent included higher expertise and being a resident of the Jackson Hole area. Factors associated with recreating with companions included younger age and lower expertise. Sex had no association with any of the surveyed safety practices. Participants were less likely to carry avalanche safety gear on low avalanche hazard days. Conclusions Certain individual characteristics of backcountry skiers and snowboarders are associated with increased frequency of adherence to recommended safety practices. These findings suggest that particular categories of backcountry recreationists may benefit from further avalanche safety education. The results of this study could help direct future educational efforts among backcountry recreationists.

International audience; In alpine terrain, blowing snow events strongly affect the local evolution of the avalanche danger and must be taken into account by avalanche hazard forecasters. This study presents the implementation and the evaluation of the blowing snow scheme Sytron into the operational chain for avalanche hazard forecasting (named S2M) used in the main French mountain ranges. S2M-Sytron provides information on blowing snow occurrence and intensity per 300-m elevation bands and aspects for several regions of the French mountains. The wind forcing is provided by the meteorological analysis system SAFRAN. S2M-Sytron was evaluated for winter 2015/16 at 11 automatic stations measuring wind speed and blowing snow fluxes in the French Alps. The system detects 55% of blowing snow days with less than 10% of false alarms. S2M-Sytron captures the occurrence of blowing snow events with and without concurrent snowfall. Improvements are obtained when considering an updated parameterization for the properties of falling snow which reduces the threshold velocity for freshly fallen snow. Using observed wind speed instead of SAFRAN wind speed to drive Sytron shows further improvements at stations where SAFRAN wind speed differs from the observations due to local topographic features. Overall, S2M-Sytron provides a regional blowing snow assessment but cannot fully reproduce the local intensity of blowing snow events.

The aims of this study was to determine how skiers' skill level concerning the assessment of avalanche risk affect how they judge avalanche terrain, how they gather information about avalanche risk, and what signs of danger they observe on a trip under considerable avalanche danger. We conducted a survey including 209 skiers, who participated in a seminar four days after several avalanches occurred in a popular ski area in Western Norway. Results showed that novices assessed the terrain for a specific site as less complex than experts, they weighted information in the avalanche forecast differently, and used different strategies to gather information about the snowpack on a trip. We also found a tendency for experts to observe more alarm signs than novices on the avalancheday. We conclude that expertise is important for making the best possible risk assessment in avalanche terrain. Management implications The level of expertise fundamentally affect how backcountry skiers assess the severity of terrain, make use of the information obtained from the avalanche forecast, and their choice of strategies for collecting information from the environment during a trip. We propose to promote the development terrain assessment skills among novice backcountry skiers first as it allows them to control their avalanche risk based on more easily interpretable observations and develop the more challenging avalanche hazard assessment skills gradually through experience.