Item: THUMBS-UP FOR ANALYTIC SNOWPACK ASSESSMENT – PUTTING NEW EAWS STANDARDS INTO PRACTICE
-
-
Title: THUMBS-UP FOR ANALYTIC SNOWPACK ASSESSMENT – PUTTING NEW EAWS STANDARDS INTO PRACTICE
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- Thomas Feistl [ Bavarian Avalanche Warning Service, Munich, Germany ]
- Franziska Ehrnsperger [ Bavarian Avalanche Warning Service, Munich, Germany ]
- Philip Luger [ Catholic University of Eichstätt-Ingolstadt, Germany ]
- Christoph Hummel [ Bavarian Avalanche Warning Service, Munich, Germany ]
Date: 2023-10-08
Abstract: Snowpack stability tests, snow profiles, and process-based analysis of terrain features and weather help avalanche professionals in assessing avalanche danger and depicting it on a temporal and spatial scale. Apart from the incidence of avalanche-prone slopes and potential avalanche size, snowpack stability is the main factor for assigning a given avalanche danger level. Last year the EAWS (European Avalanche Warning Services) sharpened their definitions of the terms used in avalanche forecasting and subdivided snowpack stability into four classes. The resulting new standards were put into practice by all the members of the EAWS last winter. At the Bavarian Avalanche Warning Service they were introduced both in training courses and in operational services. All avalanche forecasters, observers, and avalanche commissioners now use them in order to assess and communicate avalanche danger. Approximately fifty observers regularly collect snowpack information in the Bavarian Alps and forward it to the Avalanche Warning Service. In addition, avalanche commissioners permanently evaluate snowpack stability in order to assess avalanche hazards to public infrastructure such as roads and ski resorts. They monitor a total of 650 avalanche plummet paths and record their findings and all avalanche incidents in the web app LA.DOK (Avalanche Documentation and Communication Tool). Comparing observation data from winter season 2022/23 we found that the snowpack stability tests ECT (Extended Column Test) and KBT (Kleiner Blocktest, "small block test") are both suitable for directly designating, on the spot, the test result of a certain snowpack stability class. It is crucial to distinguish between fracture initiation and crack propagation to determine whether a slab can be unleashed and how much impact would be necessary to trigger it. Characteristics of slab and weak layer help to estimate potential avalanche size. Determining a weak layer´s snow grain type and size helps to predict the persistence of that layer. In order to obtain comparable results we developed a catchy method with the help of which observers and commissioners can adequately communicate and classify their test results in a standardized way. It works using your thumbs: thumbs up implies "safe situation" (no avalanche to be expected), thumbs down "immediate danger" (avalanches can release anytime). Left thumb represents fracture initiation, right thumb crack propagation. The combination of left hand and right hand leads you directly to one of the four stability classes. In the short period of one winter season we found high acceptance of this descriptive method within our diverse community which confirms its applicability. Our vision of the future is that more and more winter sports enthusiasts will now share their observations in the selfsame way and thus make their findings beneficial to everyone by contributing to avalanche warning through shared information.
Object ID: ISSW2023_P1.08.pdf
Language of Article: English
Presenter(s): Thomas Feistl
Keywords: avalanche, snowpack, stability, risk management, EAWS
Page Number(s): 184 - 189
-