Archived

Avalanche Forecast

Dec 6th, 2017–Dec 7th, 2017

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

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

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

Regions: South Rockies.

A rapid shift to warm, sunny conditions will increase the range of avalanche problems as well as their potential for reactivity.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Thursday: Mainly sunny with valley cloud due to an alpine temperature inversion. Light northwest winds. Freezing level to around 3300 metres with alpine temperatures of +4. Cooler temperatures at lower elevations.Friday: Mainly sunny with some valley cloud due to lingering temperature inversion. Light west winds. Freezing level to about 3300 metres with alpine temperatures to +5. Cooler at lower elevations.Saturday: A mix of sun and cloud. Light west winds increasing in the afternoon. Freezing level to about 3300 metres with alpine temperatures of +4. Cooler at lower elevations.

Avalanche Summary

No new avalanches have been reported from this region. There is potential for triggering wind slabs on leeward and crossloaded slopes. Smaller avalanches may also step down and trigger larger avalanches on buried weak layers deeper in the snowpack. Please submit your observations to the Mountain Information Network.

Snowpack Summary

Average snowpack depths at upper elevations in the region range from about 50-100 cm. Shifting winds over the past few days have extended wind slab formation to a wide range of aspects at treeline and above. Below the surface, the two crusts that were buried near the end of November can now be found approximately 30 cm and 60 cm down. A third crust from the end of October exists as a "facet/crust" combo near the base of the snowpack. Snowpack testing in the adjacent Kananaskis Country forecast region has yielded hard but sudden results on this layer.

Avalanche Problems

Wind Slabs

A recent wind shift from southwest to north means that fresh wind slabs are likely to now exist on a wide range of aspects at higher elevations. Be especially cautious of reverse loaded or cross-loaded slopes that see sun exposure on Thursday.

Use ridges or ribs to avoid pockets of wind loaded snow.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Loose Wet

Warm, sun-exposed slopes could produce wet loose avalanches either naturally or with rider triggers on Thursday, especially in steeper terrain.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

There are several crusts now buried within the snowpack. Use extra caution in thin snowpack areas where it may be possible to trigger a deeper layer. Triggering a wind slab may also have the potential to step-down to a deeper layer.

Be aware of triggering thin areas that may propagate to deep instabilites more easily.If triggered, wind slabs may step down to deeper layers and result in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3