Danger Sign
• Whumpf sound • Område: I denne fjellsiden. Beskrivelse: Bare et drønn på veien opp rundt 250 moh
Avalanche Activity
• 31. Jan. During the day (+01:00) • No avalanche activity
Weather
• Snow • -5 °C • 5 m/s from E ← • 50% clouds • Broken clouds most of the morning / early afternoon. Light snow on Arctowskifjellet between 1130 and 1330. Light easterly winds, fairly warm air.
Snow Cover
• 125 cm • Some snow drift • 0 cm • Snow line at 0 masl • Storm slab (soft slab) • Dry • Variable snow cover as normal for Spitsbergen. The easterly winds over the past few days have had their way with the snow cover, moving most of the fresh snow into wind deposits on westerly aspects. On Arctowskifjellet, 1F wind slabs 10-50 cm deep lie in most leeward locations. Ridges and easterly aspects I observed were blown back down to the most recent melt freeze crust. Wind has densified the most recent snow to the point that most of the snow from this week is now no longer readily available for wind transport.
Avalanche Problems
• Dry slab avalanche • Poor bonding between layers in wind deposited snow • Within half a meter • The collapsing weak layer is thin < 3 cm. • Difficult to trigger • 2 - Medium • Some steep slopes SW, W, NW • Wind slabs from earlier in the week appear to be stabilizing nicely, based on my observations. Stability tests show that it is possible to initiate a fracture in the fresh wind slabs, but these fractures are not propagating. Stomping on fresh drifts did not yield any signs of instability. In general, the wind slabs in this location felt fairly dense, homogenous, and decently well bonded.
• Dry slab avalanche • Buried weak layer of faceted snow beneath a crust • Within a meter • The collapsing weak layer is thin < 3 cm. A big and identifiable crystal in the weak layer. • Very difficult to trigger • 3 - Large • Some steep slopes SW, W, NW • So far I have only observed this avalanche problem on westerly aspects, so am a little unsure of its distribution regionally. Observed well-developed facets both over and under the most recent melt-freeze crust in the snowpack. In stability tests, the slightly larger facets under the crust were more reactive. In a modified ECT in which I removed the top 30 cm of wind slab and tested the facet layers specifically, i was able to get the facet layer under the crust to propagate after 19 (ECTP 19). However this layer is well-bridged by the hard melt-forms over it and I think it would be fairly difficult to trigger an avalanche on this layer. Nevertheless, in the event that this layer was affected by a skier, snowmobiler, or a smaller wind slab avalanche, this layer has the potential to produce sizable avalanches. Low probability / high consequence scenario.
Avalanche Danger Assessment
• Based on my observation trip today, I came up with the following inputs to ADAM: Fokksnø problemet: mulig utløsningssannsynlighet to str. 2. Vedvarende svakt lag problemet: lite sannsynlig to str. 3. This gives a moderat (2) rating. • With continued mild weather, the wind slab problem should continue to stabilize in the absence of strong winds or more precipitation. Mild weather won't make the faceted layers worse, but looks like we are probably stuck with a persistent weak layer problem for the foreseeable future. • 2 Moderate • Forecast too high • The forecast for today describes the avalanche problems well. It's possible that more snow has fallen and wind slab problems are worse further south in the region, but based on my observations in this location today, a moderate rating seems more appropriate.
