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Avalanche Forecast

Archived

Dec 18th, 2023–Dec 19th, 2023

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

Glacier.

A weak layer primed for human triggering continues to produce isolated large avalanches.

The safest way to manage this problem is through conservative terrain use.

Confidence

No Rating

Avalanche Summary

In our region 5 human triggered avalanches have occurred in the past week failing on the Dec 1st surface hoar layer. In the Connaught drainage a size 2.5 was triggered on Balu Peak, on Ursus Minor a skier narrowly avoided being carried over some cliffs and in the Asulkan valley another avalanche was triggered near the 7 steps. East of the park an experienced group triggered a size 2 avalanche on the same layer with one skier partially buried.

Snowpack Summary

20cm of soft snow covers wind affect or a thin sun crust on steep slopes in the alpine and at tree line or surface hoar in sheltered areas.

Below 2100m a rain crust is buried 40-50cm deep and beneath this, down 50-100cm a weak layer (Dec 1st surface hoar) is persisting and continues to produce 'sudden' results in snowpack tests and has been the failure plane for several recent human triggered avalanches.

In shallow areas the base of the snowpack is facetted and unsupportive.

Weather Summary

No major changes to the current vanilla weather pattern this week. Light to moderate winds with small amounts of new snow continue.

Tues: Cloudy, isolated flurries - trace of new snow, high -2 °C, light SW winds, freezing level 1700m.

Wed: Cloudy, flurries up to 7cm, low -4 °C, moderate SW winds, freezing level 1700m.

Thurs: Cloudy, isolated flurries - trace of new snow, low -5 °C, light SW winds, freezing level 1600m.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.

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.