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Erich H. Peitzsch

Publications and source records attributed to Erich H. Peitzsch.

At least 37 records · Page 2Linked to original sources
USGS2022

Assessing the seasonal evolution of snow depth spatial variability and scaling in complex mountain terrain

Dynamic natural processes govern snow distribution in mountainous environments throughout the world. Interactions between these different processes create spatially variable patterns of snow depth across a landscape. Variations in accumulation and redistribution occur at a variety of spatial scales, which are well established for moderate mountain terrain. However, spatial patterns of snow depth variability in steep, complex mountain terrain have not been fully explored due to insufficient spatial resolutions of snow depth measurement. Recent advances in uncrewed aerial systems (UASs) and structure from motion (SfM) photogrammetry provide an opportunity to map spatially continuous snow depths at high resolutions in these environments. Using UASs and SfM photogrammetry, we produced 11 snow depth maps at a steep couloir site in the Bridger Range of Montana, USA, during the 2019–2020 winter. We quantified the spatial scales of snow depth variability in this complex mountain terrain at a variety of resolutions over 2 orders of magnitude (0.02 to 20 m) and time steps (4 to 58 d) using variogram analysis in a high-performance computing environment. We found that spatial resolutions greater than 0.5 m do not capture the complete patterns of snow depth spatial variability within complex mountain terrain and that snow depths are autocorrelated within horizontal distances of 15 m at our study site. The results of this research have the potential to reduce uncertainty currently associated with snowpack and snow water resource analysis by documenting and quantifying snow depth variability and snowpack evolution on relatively inaccessible slopes in complex terrain at high spatial and temporal resolutions.

Montana↗
USGS2021

Climate drivers of large magnitude snow avalanche years in the U.S. northern Rocky Mountains

Large magnitude snow avalanches pose a hazard to humans and infrastructure worldwide. Analyzing the spatiotemporal behavior of avalanches and the contributory climate factors is important for understanding historical variability in climate-avalanche relationships as well as improving avalanche forecasting. We used established dendrochronological methods to develop a long-term (1867–2019) regional avalanche chronology for the Rocky Mountains of northwest Montana using tree-rings from 647 trees exhibiting 2134 avalanche-related growth disturbances. We then used principal component analysis and a generalized linear autoregressive moving average model to examine avalanche-climate relationships. Historically, large magnitude regional avalanche years were characterized by stormy winters with positive snowpack anomalies, with avalanche years over recent decades increasingly influenced by warmer temperatures and a shallow snowpack. The amount of snowpack across the region, represented by the first principal component, is shown to be directly related to avalanche probability. Coincident with warming and regional snowpack reductions, a decline of ~ 14% (~ 2% per decade) in overall large magnitude avalanche probability is apparent through the period 1950–2017. As continued climate warming drives further regional snowpack reductions in the study region our results suggest a decreased probability of regional large magnitude avalanche frequency associated with winters characterized by large snowpacks and a potential increase in large magnitude events driven by warming temperatures and spring precipitation.

Montana↗
USGS2021

A regional spatio-temporal analysis of large magnitude snow avalanches using tree rings

Snow avalanches affect transportation corridors and settlements worldwide. In many mountainous regions, robust records of avalanche frequency and magnitude are sparse or non-existent. However, dendrochronological methods can be used to fill this gap and infer historical avalanche patterns. In this study, we developed a tree-ring-based avalanche chronology for large magnitude avalanche events (size ≥ ∼ D 3 "> ≥ ∼ D 3 ) using dendrochronological techniques for a portion of the US northern Rocky Mountains. We used a strategic sampling design to examine avalanche activity through time and across nested spatial scales (i.e., from individual paths, four distinct subregions, and the region). We analyzed 673 samples in total from 647 suitable trees collected from 12 avalanche paths from which 2134 growth disturbances were identified over the years 1636 to 2017 CE. Using existing indexing approaches, we developed a regional avalanche activity index to discriminate avalanche events from noise in the tree-ring record. Large magnitude avalanches, common across the region, occurred in 30 individual years and exhibited a median return interval of approximately 3 years (mean = 5.21 years). The median large magnitude avalanche return interval (3–8 years) and the total number of avalanche years (12–18) varies throughout the four subregions, suggesting the important influence of local terrain and weather factors. We tested subsampling routines for regional representation, finding that sampling 8 random paths out of a total of 12 avalanche paths in the region captures up to 83 % of the regional chronology, whereas four paths capture only 43 % to 73 %. The greatest value probability of detection for any given path in our dataset is 40 %, suggesting that sampling a single path would capture no more than 40 % of the regional avalanche activity. Results emphasize the importance of sample size, scale, and spatial extent when attempting to derive a regional large magnitude avalanche event chronology from tree-ring records.

Montana↗
USGS2020

Specialized meltwater biodiversity persists despite widespread deglaciation

Glaciers are important drivers of environmental heterogeneity and biological diversity across mountain landscapes. Worldwide, glaciers are receding rapidly due to climate change, with important consequences for biodiversity in mountain ecosystems. However, the effects of glacier loss on biodiversity have never been quantified across a mountainous region, primarily due to a lack of adequate data at large spatial and temporal scales. Here, we combine high-resolution biological and glacier change (ca. 1850–2015) datasets for Glacier National Park, USA, to test the prediction that glacier retreat reduces biodiversity in mountain ecosystems through the loss of uniquely adapted meltwater stream species. We identified a specialized cold-water invertebrate community restricted to the highest elevation streams primarily below glaciers, but also snowfields and groundwater springs. We show that this community and endemic species have unexpectedly persisted in cold, high-elevation sites, even in catchments that have not been glaciated in ∼170 y. Future projections suggest substantial declines in suitable habitat, but not necessarily loss of this community with the complete disappearance of glaciers. Our findings demonstrate that high-elevation streams fed by snow and other cold-water sources continue to serve as critical climate refugia for mountain biodiversity even after glaciers disappear.

Montana↗
USGS2019

Reanalysis of the U.S. Geological Survey Benchmark Glaciers: Long-term insight into climate forcing of glacier mass balance

Mountain glaciers integrate climate processes to provide an unmatched signal of regional climate forcing. However, extracting the climate signal via intercomparison of regional glacier mass balance records can be problematic when methods for extrapolating and calibrating direct glaciological measurements are mixed or inconsistent. To address this problem, we reanalyzed and compared long-term mass balance records from the U.S. Geological Survey Benchmark Glaciers. These five glaciers span maritime and continental climate regimes of the western United States and Alaska. Each glacier exhibits cumulative mass loss since the mid-20th century, with average rates ranging from –0.58 to –0.30 m water equivalent (w.e.) a-1. We produced a set of solutions using different extrapolation and calibration methods to inform uncertainty estimates, which range from 0.22–0.44 m w.e. a-1. Mass losses are primarily driven by increasing summer warming. Continentality exerts a stronger control on mass loss than latitude. Similar to elevation, topographic shading, snow redistribution, and glacier surface features often exert first-order control on mass balance. The reanalysis underscores the value of geodetic calibration to resolve mass balance magnitude, as well as the irreplaceable value of direct measurements in contributing to process-based understanding of glacier mass balance.

Journal of Glaciology↗
USGS2019

Forecasting for dry and wet avalanches during mixed rain and snow storm events

Professionals in coastal and some inland mountain ranges regularly face mixed rain-snow events. Professionals in inland ranges frequently deal with persistent slab avalanches failing on old faceted layers buried deep within the snowpack. What happens when you combine these snowpack and weather events? Widespread avalanching involving faceted layers during mixed rain-snow events is rarely observed and is not as well-understood. Last March, USFS Sawtooth Avalanche Center (SAC) staff observed this scenario.

The Avalanche Review↗
USGS2018

Local topography increasingly influences the mass balance of a retreating cirque glacier

Local topographically driven processes – such as wind drifting, avalanching, and shading – are known to alter the relationship between the mass balance of small cirque glaciers and regional climate. Yet partitioning such local effects from regional climate influence has proven difficult, creating uncertainty in the climate representativeness of some glaciers. We address this problem for Sperry Glacier in Glacier National Park, USA, using field-measured surface mass balance, geodetic constraints on mass balance, and regional climate data recorded at a network of meteorological and snow stations. Geodetically derived mass changes during 1950–1960, 1960–2005, and 2005–2014 document average mass change rates during each period at −0.22 ± 0.12, −0.18 ± 0.05, and −0.10 ± 0.03 m w.e. yr −1 , respectively. A correlation of field-measured mass balance and regional climate variables closely (i.e., within 0.08 m w.e. yr −1 ) predicts the geodetically measured mass loss from 2005 to 2014. However, this correlation overestimates glacier mass balance for 1950–1960 by +1.20 ± 0.95 m w.e. yr −1 . Our analysis suggests that local effects, not represented in regional climate variables, have become a more dominant driver of the net mass balance as the glacier lost 0.50 km 2 and retreated further into its cirque.

Northern Rocky Mountains↗
USGS2018

On the exchange of sensible and latent heat between the atmosphere and melting snow

The snow energy balance is difficult to measure during the snowmelt period, yet critical for predictions of water yield in regions characterized by snow cover. Robust simplifications of the snowmelt energy balance can aid our understanding of water resources in a changing climate. Research to date has demonstrated that the net turbulent flux ( F T ) between a melting snowpack and the atmosphere is negligible if the sum of atmospheric vapor pressure ( e a ) and temperature ( T a ) equals a constant, but it is unclear how frequently this situation holds across different sites. Here, we quantified the contribution of F T to the snowpack energy balance during 59 snowmelt periods across 11 sites in the FLUXNET2015 database with a detailed analysis of snowmelt in subarctic tundra near Abisko, Sweden. At the Abisko site we investigated the frequency of occurrences during which sensible heat flux ( H ) and latent heat flux ( λE ) are of (approximately) equal but opposite sign, and if the sum of these terms, F T , is therefore negligible during the snowmelt period. H approximately equaled - λE for less than 50% of the melt period and F T was infrequently a trivial term in the snowmelt energy balance at Abisko. The reason is that the relationship between observed e a and T a is roughly orthogonal to the “line of equality” at which H equals - λE as warmer T a during the melt period usually resulted in greater e a . This relationship holds both within melt periods at individual sites and across different sites in the FLUXNET2015 database, where F T comprised less than 20% of the energy available to melt snow, Q m , in 44% of the snowmelt periods studied here. F T / Q m was significantly related to the mean e a during the melt period, but not mean T a , and F T tended to be near 0 W m −2 when e a averaged ca . 0.5 kPa. F T may become an increasingly important term in the snowmelt energy balance across many global regions as warmer temperatures are projected to cause snow to melt more slowly and earlier in the year under conditions of lower net radiation ( R n ). Eddy covariance research networks such as Ameriflux must improve their ability to observe cold-season processes to enhance our understanding of water resources and surface-atmosphere exchange in a changing climate.

Agricultural and Forest Meteorology↗
USGS2018

Detecting snow depth change in avalanche path starting zones using uninhabited aerial systems and structure from motion photogrammetry

Understanding snow depth distribution and change is useful for avalanche forecasting and mitigation, runoff forecasting, and infrastructure planning. Advances in remote sensing are improving the ability to collect snow depth measurements. The development of structure from motion (SfM), a photogrammetry technique, combined with the use of uninhabited aerial systems (UASs) allows for high resolution mapping of snow depth over complex terrain. The primary objective of this study was to determine the feasibility and efficacy of SfM to examine snow depth distribution and variability in complex terrain such as avalanche path starting zones at multiple times during the season. We used a 3DR Solo quadcopter UAS equipped with a Ricoh GR II camera at 90 m above ground level to acquire images of one avalanche starting zone in northwest Montana, USA. We also placed 4 to 13 ground control points (GCPs) around the area of interest to avoid traveling in steep, avalanche terrain. Ground control measurements resulted in 5 to10 cm horizontal accuracy and 5 to 15 cm vertical accuracy for 90 to 95 % of the collected points (a minimum of 100 points collected at each GCP). In-situ measurements of snow depth difference between sampling days ranged from 20 to 60 cm. We processed the images to create point clouds and digital surface models (DSMs). The resolution of the resultant DSMs was approximately 5 cm. Preliminary DSM and point cloud differencing efforts suggest relative change detection of snow depth at 5 to 15 cm resolution. The use of these relatively low cost and easily accessible methods of snow depth data collection will enhance accuracy of snow depth change estimates in starting zones and can be used to inform avalanche forecasting and mitigation efforts.

Conference Paper↗
USGS2018

Identifying major avalanche years from a regional tree-ring based avalanche chronology for the U.S. Northern Rocky Mountains

Avalanches not only pose a major hazard to people and infrastructure, but also act as an important ecological disturbance. In many mountainous regions in North America, including areas with existing transportation corridors, reliable and consistent avalanche records are sparse or non-existent. Thus, inferring long-term avalanche patterns and associated contributory climate and weather factors requires the use of dendrochronological methods...

Conference Paper↗
USGS2017

Glaciological measurements and mass balances from Sperry Glacier, Montana, USA, years 2005–2015

Glacier mass balance measurements help to provide an understanding of the behavior of glaciers and their response to local and regional climate. In 2005 the United States Geological Survey established a surface mass balance monitoring program on Sperry Glacier, Montana, USA. This project is the first quantitative study of mass changes of a glacier in the US northern Rocky Mountains and continues to the present. The following paper describes the methods used during the first 11 years of measurements and reports the associated results. From 2005 to 2015, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m w.e. (water equivalent). The mean winter, summer, and annual glacier-wide mass balances were 2.92, −3.41, and −0.40 m w.e. yr −1 respectively. We derive these cumulative and mean results from an expansive data set of snow depth, snow density, and ablation measurements taken at selected points on the glacier. These data allow for the determination of mass balance point values and a time series of seasonal and annual glacier-wide mass balances for all 11 measurement years. We also provide measurements of glacier extent and accumulation areas for select years. All data have been submitted to the World Glacier Monitoring Service and are available at doi:10.5904/wgms-fog-2016-08 . This foundational work provides valuable insight about Sperry Glacier and supplies additional data to the worldwide record of glaciers measured using the glaciological method. Future research will focus on the processes that control accumulation and ablation patterns across the glacier. Also we plan to examine the uncertainties related to our methods and eventually quantify a more robust estimate of error associated with our results.

Montana↗
USGS2016

Using structure from motion photogrammetry to examine glide snow avalanches

Structure from Motion (SfM), a photogrammetric technique, has been used extensively and successfully in many fields including geosciences over the past few years to create 3D models and high resolution digital elevation models (DEMs) from aerial or oblique photographs. SfM has recently been used in a limited capacity in snow avalanche research and shows promise as a tool for broader applications. In this study, we used SfM to examine glide avalanches along the Going-to-the-Sun Road (GTSR) corridor in Glacier National Park (GNP), Montana. Glide avalanches pose substantial hazard to railroads, highways, and other infrastructure in many avalanche prone regions around the world, and yet basic measurements of crown depth and ground/snow interface can be hard to observe. Along the GTSR, glide avalanches can impact worker and public safety, but accessing glide avalanche crowns or glide cracks is often prohibited by inaccessible terrain or residual avalanche hazard. We used SfM techniques to derive high resolution DEMs for four glide avalanches that occurred in the spring of 2016. This allowed us to estimate selected full depth glide avalanche dimensions without visiting the site. However, our analysis was limited to qualitative assessments of the glide avalanche dimensions as the high resolution coordinates necessary to analyze the vertical dimension of avalanche crowns were not available. Despite this, our results suggest SfM can be a robust tool for examining glide avalanche crowns and of sufficient resolution to accurately characterize glide avalanche dimensions. Under a warming and more variable future climate, glide avalanches could become a more prevalent problem, and using SfM as a tool to help characterize glide avalanches over a larger spatial area will help us to better document and further understand these phenomena.

Conference Paper↗
USGS2016

Case study: 2016 Natural glide and wet slab avalanche cycle, Going-to-the-Sun Road, Glacier National Park, Montana, USA

The Going-to-the-Sun Road (GTSR) is the premier tourist attraction in Glacier National Park, Montana. The GTSR also traverses through and under 40 avalanche paths which pose a hazard to National Park Service (NPS) road crews during the annual spring snow plowing operation. Through a joint collaboration between the NPS and the U.S. Geological Survey (USGS), a forecasting program primarily dealing with wet snow avalanche problems serves to aid worker safety. The objective of this case study is to examine the meteorological metrics and snowpack characteristics leading up to a noteworthy wet slab and glide avalanche cycle that occurred 16-22 April, 2016 during a period of unseasonably warm and sunny weather. Continuous above freezing temperatures at upper elevations with daily maximum values reaching 10-15° C persisted for four days. The nearby Flattop Mountain SNOTEL station reported a steady loss of SWE of approximately 1.25 cm/day. River height and discharge on the Middle Fork of the Flathead River (app. 20-35 km away from starting zones) increased from 1.26 m and 139.60 m3/s (4930 cfs), respectively, on April 18 to 1.69 m and 267.59 m3/s (9450 cfs) on April 22. The ensuing avalanche cycle began with three small glide avalanches on 17 April and culminated in three large wet slab avalanches that released on wet, basal facets. These wet slabs were triggered by glide avalanches releasing above and cascading over cliffs. Four of these avalanches crossed plowed sections of the road, resulting in a three day delay in plowing operations. Finally, this specific case was compared to previous statistical models for wet snow avalanches in this transportation corridor. Out of 12 avalanche days, the model correctly predicted six of those days as avalanche days. This case study allowed for a greater understanding of a wet slab and glide avalanche cycle that occurred during a prolonged spring warming event and can serve as a reference for future similar cycles.

Conference Paper↗
USGS2015

Terrain parameters of glide snow avalanches and a simple spatial glide snow avalanche model

Glide snow avalanches are dangerous and difficult to predict. Despite substantial recent research there is still inadequate understanding regarding the controls of glide snow avalanche release. Glide snow avalanches often occur in similar terrain or the same locations annually, and repeat observations and prior work suggest that specific topography may be critical. Thus, to gain a better understanding of the terrain component of these types of avalanches we examined terrain parameters associated with the specific area of glide snow avalanche release in comparison to avalanche starting zones where no glide snow avalanches were observed (i.e. non-glide snow avalanche terrain). Glide snow avalanche occurrences visible from the Going-to-the-Sun Road corridor in Glacier National Park, Montana from 2003 to 2013 are investigated using a database of all avalanche occurrences derived of daily observations each year from 1 April to 1 June. This yielded 192 glide snow avalanches in 53 distinct avalanche paths. Each avalanche was digitized in a GIS using satellite, oblique, and aerial imagery as reference. A set of 117 non-glide snow avalanche starting zones were also selected in this manner. These were start zones with avalanche activity potential, but without glide avalanches observed. Topographical parameters such as area, slope, aspect, curvature, potential incoming solar radiation, distance from ridge, and elevation were then derived for the entire dataset utilizing tools with a GIS and a 10 m DEM. Ground class and a glide factor were calculated using a four level classification index with in-situ observations and a land surface type layer in a GIS. A total of 21 terrain variables were examined using a univariate analysis between areas where glide snow avalanches occurred and areas where glide snow avalanches were never observed, despite crack formation. Only two variables were not significantly different. The significantly different variables were then used to train a classification tree to distinguish between glide and non-glide snow avalanche terrain. A 10-fold cross validated tree resulted in four decision nodes to classify the data. The nodes split on glide factor, maximum slope angle, seasonal sum of incoming solar radiation, and maximum curvature to distinguish between glide snow avalanche and non-glide snow avalanche terrain with an unweighted average accuracy (RPC) of 0.95 and probability of detection of events (POD) of 0.99. Finally, the results of the cross-validated tree were used in a GIS to examine other areas, not used in the training dataset of the classification tree, of potential glide snow avalanche release within Glacier National Park. Using this understanding of the role of topographic parameters on glide snow avalanche activity, a spatial terrain based model was developed to identify other areas with high glide snow avalanche potential outside of the immediate observation area. This simple spatial model correctly classified 78 percent of actual glide snow avalanche terrain (pixel count) of a small test area of four independent observed glide snow avalanches.

Montana↗
USGS2014

Assessing the importance of terrain parameters on glide avalanche release

Glide snow avalanches are dangerous and difficult to predict. Despite recent research there is still a lack of understanding regarding the controls of glide avalanche release. Glide avalanches often occur in similar terrain or the same locations annually and observations suggest that topography may be critical. Thus, to gain an understanding of the terrain component of these types of avalanches we examined terrain parameters associated with glide avalanche release as well as areas of consistent glide crack formation but no subsequent avalanches. Glide avalanche occurrences visible from the Going-to-the-Sun Road corridor in Glacier National Park, Montana from 2003-2013 were investigated using an avalanche database derived of daily observations each year from April 1 to June 15. This yielded 192 glide avalanches in 53 distinct avalanche paths. Each avalanche occurrence was digitized in a GIS using satellite, oblique, and aerial imagery as reference. Topographical parameters such as area, slope, aspect, elevation and elevation were then derived for the entire dataset utilizing GIS tools and a 10m DEM. Land surface substrate and surface geology were derived from National Park Service Inventory and Monitoring maps and U.S. Geological Survey surface geology maps, respectively. Surface roughness and glide factor were calculated using a four level classification index. . Then, each avalanche occurrence was aggregated to general avalanche release zones and the frequencies were compared. For this study, glide avalanches released in elevations ranging from 1300 to 2700 m with a mean aspect of 98 degrees (east) and a mean slope angle of 38 degrees. The mean profile curvature for all glide avalanches was 0.15 and a plan curvature of -0.01, suggesting a fairly linear surface (i.e. neither convex nor concave). The glide avalanches occurred in mostly bedrock made up of dolomite and limestone slabs and talus deposits with very few occurring in alpine meadows. However, not all glide avalanches failed as cohesive slabs on this bedrock surface. Consequently, surface roughness proved to be a useful descriptive variable to discriminate between slopes that avalanched and those that did not. Annual 'repeat offender' glide avalanche paths were characterized by smooth outcropping rock plates with stratification planes parallel to the slope. Combined with aspect these repeat offenders were also members of the highest glide category. Using this understanding of the role of topographic parameters on glide avalanche activity, a spatial terrain based model was developed to identify other areas with high glide avalanche potential outside of our immediate observation area.

Montana↗
USGS2012

Examining spring wet slab and glide avalanche occurrence along the Going-to-the-Sun Road corridor, Glacier National Park, Montana, USA

Wet slab and glide snow avalanches are dangerous and yet can be particularly difficult to predict. Wet slab and glide avalanches are presumably triggered by free water moving through the snowpack and the subsequent interaction with layer or ground interfaces, and typically occur in the spring during warming and subsequent melt periods. In Glacier National Park (GNP), Montana, both types of avalanches can occur in the same year and affect the spring opening operations of the Going-to-the-Sun Road (GTSR). We investigated the timing of wet slab and glide avalanche occurrence along the GTSR from 2003 to 2011 using meteorological and snowpack data from two high-elevation weather stations, one SNOTEL site, and an avalanche database to characterize 55 wet slab and 182 glide avalanches. Daily wet slab and glide avalanche occurrence were combined to represent an avalanche day and were compared to non-avalanche days (no avalanche occurrence) for 60 variables (both direct and derived measurements) using a univariate analysis. A classification tree (CART) was then trained to capture the most important variables for examining specific meteorological and snowpack variables that contribute to these types of wet snow avalanches. The CART was 10-fold cross validated using the data for 2003–2010 seasons and resulted in overall predictive accuracy of 73%. We then used the statistically optimal CART as a predictive model for the spring avalanche season of 2011, which resulted in an overall predictive accuracy of 82% for both avalanche and non-avalanche days, and a predictive accuracy of 91% for avalanche days. The results suggest that the role of air temperature and snowpack settlement appear to be the most important variables in wet slab and glide avalanche occurrence. When applied to the 2011 season, the results of the CART model are encouraging and they enhance our understanding of some of the required meteorological and snowpack conditions for wet slab and glide avalanche occurrence.

Cold Regions Science and Technology↗
USGS2012

Time lapse photography as an approach to understanding glide avalanche activity

Avalanches resulting from glide cracks are notoriously difficult to forecast, but are a recurring problem for numerous avalanche forecasting programs. In some cases glide cracks are observed to open and then melt away in situ. In other cases, they open and then fail catastrophically as large, full-depth avalanches. Our understanding and management of these phenomena are currently limited. It is thought that an increase in the rate of snow gliding occurs prior to full-depth avalanche activity so frequent observation of glide crack movement can provide an index of instability. During spring 2011 in Glacier National Park, Montana, USA, we began an approach to track glide crack avalanche activity using a time-lapse camera focused on a southwest facing glide crack. This crack melted in-situ without failing as a glide avalanche, while other nearby glide cracks on north through southeast aspects failed. In spring 2012, a camera was aimed at a large and productive glide crack adjacent to the Going to the Sun Road. We captured three unique glide events in the field of view. Unfortunately, all of them either failed very quickly, or during periods of obscured view, so measurements of glide rate could not be obtained. However, we compared the hourly meteorological variables during the period of glide activity to the same variables prior to glide activity. The variables air temperature, relative humidity, air pressure, incoming and reflected long wave radiation, SWE, total precipitation, and snow depth were found to be statistically different for our cases examined. We propose that these are some of the potential precursors for glide avalanche activity, but do urge caution in their use, due to the simple approach and small data set size. It is hoped that by introducing a workable method to easily record glide crack movement, combined with ongoing analysis of the associated meteorological data, we will improve our understanding of when, or if, glide avalanche activity will ensue.

Montana↗