Wind Slabs
N
NE
E
SE
S
SW
W
NW
- Alpin
- Limite forestière
- Sous la limite forestière
- Probabilité
- Likely
- Taille
- 1–3
Be alert for wind slabs below ridge crests, behind terrain features, and in cross-loaded gullies.
Bulletin d’avalanche
Voir sur la carteKootenay Boundary
Dec 28 – 29, 2011Avalanche Canada
Archivé · expiré 15 years ago
Danger d’avalanche
Fri
Sat
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué
Problèmes avalancheux
Persistent Slabs
NNEESESSWWNW- Alpin
- Limite forestière
- Sous la limite forestière
- Probabilité
- Very Likely
- Taille
- 2–5
Enough snow has built up above a very touchy buried surface hoar layer that we are seeing many avalanches fail on this layer.
Storm Slabs
NNEESESSWWNW- Alpin
- Limite forestière
- Sous la limite forestière
- Probabilité
- Possible - Likely
- Taille
- 1–3
Recent snow has fallen with a warming trend. This is likely to have created slab conditions within the new snow. A storm slab could step down to a persistent weak layer, creating a large avalanche.
Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain
Weather Forecast
Wednesday night: 10-15cm. Moderate to strong west to south-west winds. Freezing level lowering to 1300m.Thursday: Light snowfall. Light-moderate north-westerlies. Freezing level around 900m.Friday: Moderate to heavy snow. Strong south-west winds. Freezing level around 1000m. Saturday: Light flurries. Cooling temperatures. Light north-westerly winds.
Avalanche Summary
We are now in an avalanche cycle with numerous natural and human-triggered avalanches occurring, reported as up to size 2.5. Many of these are failing on the mid-December surface hoar, mostly on north through east aspects from 1500m to the peaks. A skier remotely triggered an avalanche from 50m away and in many places shooting cracks and whumphing are further indicators of a very touchy, unstable snowpack.
Snowpack Summary
The snowpack is in a very touchy state. 30-50cm of storm snow has built up over a weak old snow surface. The storm snow has turned into a soft slab due to warming. South-west winds have led to the development of wind slabs on lee slopes. The surface hoar layer buried in mid-December is now under 45-70cm of snow and is highly reactive. It is well-preserved with 10-15mm crystals and exists into alpine start zones (although it's probably best preserved in sheltered areas near treeline). The mid-pack is generally well settled. Facets exist at the base of the snowpack.