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Archived

Avalanche Forecast

Dec 8th, 2022–Dec 9th, 2022
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Reactive wind slabs may exist at upper elevations. More sheltered areas are likely to have preserved and buried a persistent weak layer that has shown reactivity in snowpack tests.

Keep your terrain choices conservative and assess conditions while you travel. Watch and feel for signs of instability such as whumpfing, cracking, and new avalanches.

Confidence

Moderate

Avalanche Summary

No new natural avalanches observed since the weekend. Avalanches triggered with explosives, that were focused on wind slabs, were reported by local operators. These were small size one avalanches.

This past Sunday, a MIN report from Tunnel Creek reported reactivity in a snowpack test on the Mid-November layer on a south aspect. They also observed a large natural avalanche on a west-facing slope at treeline.

With continued moderate to strong winds and slightly warmer temperatures, wind slabs may be reactive. Loose-dry avalanches (sluffing) of the surface snow from steep slopes and terrain features should also be expected.

Snowpack Summary

In less than a week, about 40 cm of low-density snow has fallen. Southwesterly winds have redistributed much of this snow, building fresh wind slabs. In sheltered terrain, slightly warmer temperatures may start to consolidate the recent snow into more of a slab.

The middle of the snowpack consists of weak sugary layers of facets and surface hoar. A widespread rain crust remains near the ground, at treeline, and below treeline.

At treeline, snowpack depths vary from 120-200 cm.

Weather Summary

Thursday Night

Mainly cloud, 5 cm accumulation, winds southwest 20 gusting to 45 km/h, temperature -6 C at 1500 m.

Friday

Cloudy with possible sunny periods, 2 cm accumulation, winds southwest 15 gusting to 35 km/h, temperature -4 C at 1500 m.

Saturday

Mainly cloudy, trace accumulation, winds south 10 km/h, temperature -5 C at 1500m.

Sunday

Cloudy with sunny periods, 3 cm accumulation, winds south 10 km/h, temperature -3 C at 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

Avalanche Problems

Wind Slabs

Westerly, switching to the southwest, winds combined with new snow have built reactive wind slabs in the alpine and open areas at treeline.

Small avalanches in the upper snowpack could trigger deeper weak layers, creating a larger-than-expected avalanche.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 1.5

Persistent Slabs

Buried layers of surface hoar and facets have been reactive to human triggers in recent days. Reactivity has been observed in sheltered areas at treeline, where the surface hoar may be preserved, and in wind-loaded areas at upper elevations, where a cohesive slab has been formed above.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 2.5