Wind Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 1–2
Strong winds will continue to redistribute 9-12" of storm snow Tuesday night into early Wednesday with a cooling trend. Slabs will be reactive to start the day and could be large. Expect increasing hazard with larger slabs that are firmer and more difficult to steer around above treeline. If you choose to ease onto windward slopes, choose slopes less than 35 degrees, avoiding poorly supported convex rollovers. Throughout this storm cycle, we've seen slabs triggered near ridgelines, but also well down onto mid-slope features. In this case, as winds begin to ease, we think slabs will be more likely in typical start zones, but can't rule out more isolated trigger locations mid-slope. In less wind-affected terrain, the upper snowpack should be right-side-up, meaning the density increases with depth. This creates excellent riding conditions, but if you transition to a firm wind skin, cracking snow surfaces, or unpleasant riding conditions, you may have found yourself on a wind slab. Anticipate these areas by noting the locations of sharp cornices on the slopes above, wind ripples on the snow surface, or rounded pillows. When in doubt, stick to wind-scoured terrain or slopes less than 35 degrees.
In wind-sheltered terrain in the upper below treeline band, you could find wind-drifted pockets where a small slab could be impactful in high-consequence terrain. You are also likely to encounter storm instabilities generated by high snowfall rates late Tuesday. Hand shear tests can help you identify layers with a propensity to slide before you consider easing into more open or steeper terrain.
Example: Shooting crack in wind-drifted snow. A red flag that shouldn't be ignored.
Photo: Joe Dellaporta