Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
A bump in westerly winds may begin to drift the low-density snow into shallow and reactive slabs on exposed slopes during the day. Look for signs of wind transported snow such as blowing snow, sharp drifts, small cornices, and wind rippled snow. If you observe any of these, steer around those areas on steep slopes. Loose avalanches, otherwise known as 'sluffs' may pose a threat in very steep terrain. Plan your ride so that you manage your sluff in steeper terrain and remember to never ride on top of other people in this environment. Always check how the snow is reacting by using small, inconsequential test slopes before entering larger slopes.
Deeper and more surprising avalanches are unlikely, but not impossible. If venturing up high, you might consider still avoiding complex and unsupported terrain because of this. We have very limited information on the upper elevation snowpack, but we do know that a deeply buried crust layer has created avalanches in the neighboring East North zone and perhaps at Snoqualmie (see photo below). Listen for whumphing collapses as you travel, they're the snowpack's way of telling you that a deeper layer is unstable. You can dig down and use snowpack tests to check how snow is bonding to the crusts from late November and early December.
Drifts covering the skin track a few hours later are a sign that wind is drifting snow. Photo: Matt Primomo