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Archived

Avalanche Forecast

Dec 13th, 2013–Dec 14th, 2013
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
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
Alpine
4: High
The avalanche danger rating in the alpine will be high
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.

Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Weather Forecast

There is a break in between storms today, with only trace amounts of snow forecast, alpine temps rising to -3 and ridge top winds SW-20 gusting to 60 km/h. Freezing levels today will be ~1200m. The next system will hit the park on Saturday, expect around 5 cm of snow on Saturday and Sunday.  Snow continues through the forecast period till Tuesday.

Snowpack Summary

35-45cm of storm snow sits over the December 8 surface hoar layer at lower elevations and over variable wind slabs up high. The storm snow is mainly low density with some soft slab developing as temps warm. The November 28 surface hoar layer is down around 50-65cm over a facetted mid-lower snowpack. The Nov 12 surface hoar layer is down 70-120cm.

Avalanche Summary

4 size 2-2.5 natural slab avalanches were observed from steep terrain off Mt Tupper and Mt MacDonald on the highway corridor. One natural avalanche, size 3 was also observed yesterday from a north aspect, likely triggered by wind loading. Sluffing of the low density surface snow was observed in unsupported terrain, steeper than 35 degrees.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

Slabs are forming in over 40cm of storm snow.  Use caution in terrain over 30 degrees. Rider triggering is possible.  Fast sluffing is likely and will pick up large amounts of snow.  Avoid exposure to terrain traps.
Make observations and assess conditions continually as you travel.Parking, eating lunch, and regrouping in runout zones is bad practice.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Watch for soft slabs on lee features at and above tree-line. Large amounts of light snow will be transported by SW winds.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

A weak layer buried in early November is present at the bottom of the snowpack. If you are able to trigger the weak layer, a large consequence avalanche will result.
Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 4