Wind Slabs
- Alpin
- Limite forestière
- Sous la limite forestière
- Probabilité
- Possible
- Taille
- 1
Hard wind slabs are the avalanche concern at this time. This problem exists above treeline and near treeline on NW-N-NE-E-SE aspects. Instability lingers despite strength gains in the upper snowpack since the peak of instability on Dec 18. Minimal snow is available for drifting with today's strong SW winds. Any new wind slabs that form today will be small. The main focus is on the older wind slabs capable of creating size D2 avalanches with significant consequences from wide propagation and hard slab blocks in the debris flow.
Locations where drifting snow was deposited as hard wind slabs on top of much softer near surface facets are problematic. Areas near treeline on NW-N-NE-E aspects that have both protection from previous NE winds and hards slabs from the recent SW winds are of particular concern. Heightened concern also exists for couloir features as greater snowpack variability over short distances is frequently encountered there.
Human triggering of hard wind slabs often occurs once an individual is well out onto the slab, close to a thinner slab trigger point such as an exposed rock, and often not by the first person on the slope.
Use the clues of recently wind drifted snow to identify areas of wind slab and adjust routes accordingly. Recently wind drifted snow exists below cornices, at and below rounded wind pillows, and where indicated by wind scouring vs deposition patterns along ridgelines.
New photos of the Dec 18 avalanche. For the photo on the right, the crown extended out of view past the prominent dead tree and around the corner for another 250 feet.