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Avalanche Forecast

Archived

Mar 13th, 2022–Mar 14th, 2022

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Sea To Sky.

Watch for fresh storm slabs building throughout the day. Be aware of the potential for large avalanches due to the presence of a buried weak layer.

Confidence

Moderate - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

Sunday night: Snowfall 5-15 cm, 40-60 km/h southwest wind, alpine temperature -5 C. Freezing level 1200 m.

Monday: Snowfall, accumulation 10-20 cm, 40-60 km/h southwest wind, alpine temperature -4 C. Freezing level 1400 m.

Tuesday: Snowfall 15-25 cm, 30-50 km/h southwest wind, alpine temperature -5 C. Freezing level 1300 m.

Wednesday: Overnight snowfall 5-15 cm then cloudy, 10-20 km/h southwest wind, treeline temperature -7 C. Freezing level 1300 m.

Avalanche Summary

On Saturday, a few skier controlled size 1 loose dry and soft wind slab avalanches were reported.

Persistent slab activity has dwindled since last week. The most recent activity was on Tuesday when two avalanches were triggered by riders on northeast aspects at treeline and alpine elevations, similar to the trend of previous avalanches. It remains possible that humans could trigger this layer, where it exists.

Snowpack Summary

New snow and southwest wind have likely formed wind slabs in lee terrain features. The snow accumulates over a thin layer of variably wind affected, faceted snow or surface hoar that overlies a hard melt-freeze crust found on all aspects below around 1500 m and on sun-exposed slopes into the alpine.

Around 40 to 80 cm deep, a weak layer of sugary faceted grains may be found above a melt-freeze crust that formed in February. This layer has been most prevalent on north to northeast aspects between 1600 m and 2100 m. Check out this forecaster blog for more info. The current storm will provide us with feedback on the reactivity of this layer.

There are no deeper concerns at this time.

Terrain and Travel

  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Avoid areas with overhead hazard.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.