Item: Synoptic Climatology of Deep Slab Avalanches in the Western United States
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Title: Synoptic Climatology of Deep Slab Avalanches in the Western United States
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Andrew Schauer [ Snow and Avalanche Laboratory, Department of Earth Sciences, Montana State University, Bozeman, MT, USA ]
- Jordy Hendrikx [ Snow and Avalanche Laboratory, Department of Earth Sciences, Montana State University, Bozeman, MT, USA ]
- Karl Birkeland [ U.S. Forest Service National Avalanche Center, Bozeman, MT, USA ] [ Snow and Avalanche Laboratory, Department of Earth Sciences, Montana State University, Bozeman, MT, USA ]
- Megan Higgs [ Department of Mathematical Sciences, Montana State University, Bozeman, MT, USA ]
Date: 2018-10-07
Abstract: Deep slab avalanches result from season-long weather beginning with the formation of snow stratigraphy conducive to deep slab avalanches. The onset of deep slab activity is commonly preceded by heavy snowfall, wind, rain-on-snow, or rapid warming events. Local slope weather (or surface weather) is mainly driven by atmospheric circulation at higher altitudes. The field of synoptic climatology relates these atmospheric processes to surface observations. Previous work has investigated the meteorology of deep slab avalanches, as well as the synoptic climatology of snowfall and avalanche occurrence in several different locations around the world. However, there is limited research that specifically relates atmospheric circulation to deep slab avalanches. This work aims to bridge a knowledge gap by investigating the synoptic climatology of deep slab avalanches across the western United States. We obtained daily 500 mb geopotential height maps from the NCEP/NCAR Reanalysis dataset for 38 consecutive winter seasons from 1979-2017, resulting in over 6,000 days of data. We have classified these daily 500 mb height maps using Self-Organizing Maps (SOM) to obtain 20 summary map patterns characterizing the observed modes of atmospheric variability over western North America and the eastern Pacific. We used Westwide Avalanche Network (WAN) data from three ski resorts across the western U.S. that represent the three dominant snow climates (maritime, continental, and intermountain) and count the number of deep slab avalanche events for each synoptic type at each location. We investigate which synoptic types tend to occur immediately prior to deep slab avalanche events. Our work improves our understanding of the relationship between atmospheric circulation and deep slab avalanches, thereby enabling practitioners to better anticipate deep slab avalanche events.
Object ID: ISSW2018_P12.8.pdf
Language of Article: English
Presenter(s):
Keywords: Avalanche forecasting, snow instability, sensitivity, model uncertainties
Page Number(s): 1191-1195
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