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Archived

Avalanche Forecast

Feb 11th, 2015–Feb 12th, 2015
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
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Conditions will remain tricky until temperatures cool. Avalanche activity continues to occur sporadically during brief periods of precipitation or sun. Minimize exposure to overhead avalanche terrain and slopes threatened by cornices.

Weather Forecast

Wed and Thurs will be mainly cloudy with flurries. Freezing levels remain around 1800m with alpine temps steady at -1'C. On Friday, freezing levels rise to 2800m with an alpine high of +2'C. Wet flurries at ridgetop and light rain at lower elevations are forecast, although amounts are light.  Throughout the forecast moderate SW winds are expected.

Snowpack Summary

Up to 20cm of snow has buried moist snow from the weekends rain. 140cm have fallen since Feb 1 and settled to ~1m of settled storm snow over the Jan 30 layer. This layer formed a crust to 2200m with spotty surface hoar distribution. Jan 15 surface hoar layer is down 100-150cm and continues to be reactive in tests.

Avalanche Summary

Avalanche activity continues during periods of precipitation, with large avalanches running into fans.  Reports from skiers in the region are of touchy conditions, with remote triggering of slabs up to 1m deep and wide propagations. Below 1500m moist snow is touchy and easily triggered by skiers, especially on steep gully like features.

Confidence

Timing or intensity of solar radiation is uncertain

Avalanche Problems

Persistent Slabs

Persistent weak layers within the top 150cm of the snowpack should not be forgotten. They continue to be reactive, and produce very large avalanches. Smaller avalanches or cornice failures may step down and propagate on these deep instabilities.
If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 4

Storm Slabs

A warm, wet and windy storm over the weekend created a storm slab that is up to 1m deep. On lee slopes, wind loading may have made this slab much deeper and more reactive. Tests indicate that the slab is stabilizing, but triggering is still possible.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.The new snow will requires several days to settle and stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Loose Wet

Small avalanches are easily triggered by skiers below ~1500m where wet snow runs easily on the crust below. Once moving they gain mass until the slope lessens. Although small these wet slides could easily hurt a skier, or bury them in a terrain trap.
Be very cautious with gully features.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 2