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Archived

Avalanche Forecast

Jan 1st, 2014–Jan 2nd, 2014
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
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: Purcells.

A number of significant avalanches have occurred in the north of this region and just beyond its northern boundary. Check the forecaster blog. Use caution if traveling in the backcountry at this time.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Thursday: An incoming storm will build through the day and likely peak some time in the late afternoon. Around 10 cm new snow likely by the afternoon. Freezing levels rising briefly to around 1300 m. Winds gusting to 50 km/h from the SW at ridgetop.Friday: Light precipitation in the morning with a few more cm or so of new snow. Freezing levels should fall back to surface, with treeline temperatures of around -7C. Winds 20-30 km/h from the NW.Saturday: A clearing trend with some sunny breaks. Temperatures falling to around -10C. Winds increasing from the NW in the afternoon at all elevations as arctic air starts to descend from the north.

Avalanche Summary

A number of significant avalanches have been reported from the north of this region and just beyond its boundary to the north. One very large (size 3) avalanche was reported on Tuesday on a N aspect at 2200 m from relatively gentle terrain with a fracture depth of 100 cm. Two large (size 2) avalanches were reported from near Golden on Monday, likely triggering buried surface hoar from 10-Dec down around 50 cm. A size 3 natural avalanche was reported from the Bugaboos on Sunday on a NE aspect at 2650m, triggered by a cornice release that pulled out a large slab all the way to ground on the slope below. Outside the boundary of this region to the north of Golden, there was an incident in the Hope Creek drainage, where four people were involved (with two sustaining injuries) in a size 3 avalanche in an alpine feature on a NE aspect.

Snowpack Summary

Up to 25 cm of recent storm snow has been redistributed by moderate to strong northwest and southwest winds. In the upper metre of the snowpack a couple of persistent weak layers exist. The upper one comprises surface hoar and is buried around 40-50 cm. The lower one comprises a facet/crust combo and is buried 80-100 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last 10 days have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.

Avalanche Problems

Deep Persistent Slabs

The most likely place to trigger a deeper layer is on a steep, convex, north-facing slope in an area with a relatively shallow snowpack.
Avoid areas with overhead hazard.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 5

Persistent Slabs

A weak layer buried around 50 cm has become reactive and can be readily triggered, especially at higher elevations on a variety of aspects.
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Good day to make conservative terrain choices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 5

Storm Slabs

New storm snow has been poorly bonding to the existing snowpack. Forecast new snow and winds will increase the likelihood of triggering an avalanche.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 4