Wind Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Likely
- Dimensione
- 1–2
Very strong winds built shallow but reactive wind slabs Monday. Meadows Pro Patrol reported easily triggering widely propagating wind slabs without the use of explosives. Wind slabs triggered Monday morning were generally in the 4-6" range, but wind transport continued through the day. Wind slabs which you could trigger Tuesday will be thicker, but still widely propagating. Wind transport was intense, however, snow accumulation was modest at lower elevations, so expect larger potential avalanches as you ascend. The onset of precipitation Monday morning coincided with plummeting temperatures and, as a result, Monday's snowfall is poorly bonded to the melt-freeze crust from the weekend's nice weather. A layer of low-density snow lies between the weekend's crust and still enlarging wind slabs. In wind-sheltered areas below treeline, a layer of surface hoar has been preserved and in other areas, the reactive layer is simply low-density snow beneath a wind slab. Regardless of the culprit, a layer of reactive snow is buried between Monday's wind affected snow and the firm surfaces from the weekend. Take note of recent cornice development, give them wide berth and steer around slopes directly below cornices where snow deposits are likely. Identify and avoid wind loaded slopes where you see firm and textured snow surfaces, cracking or whumphing in the snow as you travel, and pillow-like features.
As always, use blowing snow and cornice formation as visual clues where slabs may be forming. Hollow sounding and firm or textured snow are other clues that wind transport is building slabs. The winds have been strong enough that slabs have developed further downslope than normal so be alert for cross-loaded terrain features and midslope slab formation. Winds are forecast to shift direction and freshly drifting snow will cover some of our most obvious clues to wind slab formation. Choose terrain conservatively through this transitional weather period and choose conservative routes away from start zones and steep lee slopes when in doubt.
Blowing snow, firm and textured snow, and cornice formation are all evidence that wind slabs are likely to be forming on lee slopes.