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Archived

Avalanche Forecast

Mar 5th, 2016–Mar 6th, 2016
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Glacier.

Thoughtful terrain selection and conservative group management are essential during this period of considerable avalanche danger.

Weather Forecast

Precipitation will ease late this afternoon but expect moist snow and rain below 2000m. Possible sunny breaks later in the day with alpine temperatures reaching zero and moderate to strong SW winds. Freezing levels drop overnight and climb again with the arrival of another frontal system on Sunday morning with an additional 10mm of snow and rain.

Snowpack Summary

5 cm of moist snow overnight. 65cm of storm snow overlies the Feb 27 layer, which is a crust on SE-W aspects, widespread surface hoar/stellars on shaded aspects. Large cornices and reactive wind slabs on lee features. Feb 10 surface hoar/ crust layer is down 100cm and is unreactive in tests. Snow is moist below 1900m. Rain this morning up to 1250m.

Avalanche Summary

A widespread natural avalanche cycle was observed in the highway corridor. Wind slab releases on polar aspects, loose solar triggered on solar aspects and one large cornice triggered avalanche that ran size 3. Several size 1.5 wind slab avalanches were observed in the backcountry. These avalanches were on a wind loaded east aspect.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Wind Slabs

Ongoing strong southerly winds have created reactive slabs on lee features. Likely locations for these slabs are northerly aspects near ridge line and crossloaded ribs in valleys that channel the winds.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

The Feb 27 crust/ surface hoar layer is down 60cm and produces sudden results in stability tests. When triggered, this layer could propagate into a large avalanche. With warming temperatures this layer could fail as a moist slab at lower elevations.
Avoid convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 3

Cornices

New snow and strong winds have contributed to cornice development. Warm temperatures and periods of sun may be enough to cause cornices to fail today. Cornice failures have potential to trigger persistent slabs on slopes below, with big consequences.
Extra caution needed around cornices with current conditions.Minimize overhead exposure to cornices above.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3