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Avalanche Forecast

Archived

Apr 13th, 2024–Apr 14th, 2024

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Northwest Coastal, Boundary, Kitimat, Nass, Rupert, Seven Sisters, Shames, Stewart, Howson.

Watch for signs of instability as you move through terrain.

A deeply buried weak layer from early April remains rider triggerable.

Confidence

Moderate

Avalanche Summary

Many slab avalanches were observed on Thursday, the majority of these avalanches occurred in the north of the region. The avalanches were triggered naturally and by riders in alpine terrain on all aspects. The avalanches were 40 to 80 cm deep and occurred within the recent storm snow as well as on the weak layer from early April. Remotely triggered avalanches involving this layer have also been reported. 

Snowpack Summary

Recent snow and southwest wind formed wind slabs in lee terrain features at higher elevations. A crust exists on or near the surface on south and west facing slopes at treeline and above. Below treeline the snow surface is moist.

Around 50 to 100 cm of snow overlies a hard melt-freeze crust from early April. This snow is slow to bond to the crust where pockets of weak surface hoar or faceted grains rest on the crust, which is most likely on northerly aspects at treeline and alpine elevations.

There are no deeper concerns at this time.

Weather Summary

Saturday Night

Mostly cloudy with up to 5 cm of new snow. 15 to 35 km/h southwest alpine wind. Treeline temperature -4°C.

Sunday

A mix of sun and cloud with 2 to 4 cm of new snow in AM. 20 to 40 km/h southwest alpine wind. Freezing level rising to 1100 m.

Monday

A mix of sun and cloud with 1 to 3 cm of new snow.  10 to 20 km/h west alpine wind. Freezing level rising to 1000 m.

Tuesday

Sunny. 5 to 15 km/h northeast alpine wind. Freezing level rising to 1200 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Carefully evaluate steep lines for wind slabs.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.