Item: Monitoring diurnal near-surface faceting
Title: Monitoring diurnal near-surface faceting
Proceedings: 2010 International Snow Science Workshop
Authors: Brett Kobernik*, Forest Service Utah Avalanche Center, Salt Lake City, Utah Wendy Wagner, University of Utah, Dept. of Atmospheric Sciences, Salt Lake City, Utah
Abstract: Near-surface faceting produces weak snow grains at or near the snow surface and once buried has the potential to form weak layers in the snowpack structure. A significant number of fatal avalanche accidents involve buried near-surface facets as the weak layer, and over the last three winter seasons have been responsible for 10 out of 11 avalanche fatalities in Utah. To gain insight into the formation of near-surface faceting, iButtons (watch battery sized self contained temperature dataloggers) were employed to monitor the snowpack temperature profile. The iButtons were stacked on a mounting strip and deployed into the snowpack to record temperatures around the clock at different levels within the snow, primarily in the top 5 cm. Preliminary testing of the iButtons has shown promise. Two distinct near-surface faceting periods were captured in the Wasatch Mountains of Utah, which after burial lead to almost 400 reported human triggered avalanches, including three fatalities and numerous close calls. A primary goal for this study is to provide forecasters with an easy and practical method for collecting snow temperature profiles which may lead to a more intimate knowledge of the snow structure and nearsurface faceting in their region. With more practitioners recording and analyzing snowpack properties, we hope to encourage more experimentation, possibly revealing a better understanding of this phenomena.
Keywords: near-surface faceting, snowpack structure, fatalities, ibuttons