Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1
As the winds increased last night, they may have grown strong enough to move soft snow remaining on windward aspects across ridges to leeward aspects. This wind-loading could have started to form some new wind slabs on NW-N-NE-E-SE aspects in near and above treeline terrain. Since the wind speeds have hovered near the threshold for transporting snow, significant uncertainty exists concerning the size and extent of these new wind slabs. If wind slabs do exist, they could rest on top of weak layers in the form of buried surface hoar making them easier for people to trigger. Wind transport could continue today allowing these wind slabs to become larger and more widespread. Avalanches resulting from these growing wind slabs could involve enough snow to bury or injure a person (size D2) in some areas.
Signs that wind slabs may exist on a slope include cornices above a slope, wind drifts/pillows, ripples and other wind-created features on the snow surface, and current blowing snow. While many of these wind slabs may remain small, the fact that they may rest on a layer of buried surface hoar would make them more difficult to manage. Surface hoar can allow remote triggering of avalanches and can allow avalanches to propagate across wider areas and run farther downslope. If doubts or uncertainty exist about whether or not an unstable wind slab has formed on a slope, assume the slope is unstable and avoid it. Avoiding wind-loaded terrain where problematic wind slabs may exist represents a great way to manage today's potential avalanche problem and to enjoy the cold soft snow that still exists in many more-sheltered, non-wind-exposed areas.