Meteorological variables to aid forecasting deep slab avalanches on persistent weak layers

Cold Regions Science and Technology
By: , and 

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Abstract

Deep slab avalanches are particularly challenging to forecast. These avalanches are difficult to trigger, yet when they release they tend to propagate far and can result in large and destructive avalanches. We utilized a 44-year record of avalanche control and meteorological data from Bridger Bowl ski area in southwest Montana to test the usefulness of meteorological variables for predicting seasons and days with deep slab avalanches. We defined deep slab avalanches as those that failed on persistent weak layers deeper than 0.9 m, and that occurred after February 1st. Previous studies often used meteorological variables from days prior to avalanches, but we also considered meteorological variables over the early months of the season. We used classification trees and random forests for our analyses. Our results showed seasons with either dry or wet deep slabs on persistent weak layers typically had less precipitation from November through January than seasons without deep slabs on persistent weak layers. Days with deep slab avalanches on persistent weak layers often had warmer minimum 24-hour air temperatures, and more precipitation over the prior seven days, than days without deep slabs on persistent weak layers. Days with deep wet slab avalanches on persistent weak layers were typically preceded by three days of above freezing air temperatures. Seasonal and daily meteorological variables were found useful to aid forecasting dry and wet deep slab avalanches on persistent weak layers, and should be used in combination with continuous observation of the snowpack and avalanche activity.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Meteorological variables to aid forecasting deep slab avalanches on persistent weak layers
Series title Cold Regions Science and Technology
DOI 10.1016/j.coldregions.2015.08.007
Volume 120
Year Published 2015
Language English
Publisher Elsevier Science
Publisher location New York, NY
Contributing office(s) Northern Rocky Mountain Science Center
First page 227
Last page 236
Country United States
State Montana
Other Geospatial Bridger Bowl ski area
Online Only (Y/N) N
Additional Online Files (Y/N) N