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Archived

Avalanche Forecast

Dec 31st, 2013–Jan 1st, 2014
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: 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

Good

Weather Forecast

Wednesday: Dry in the morning with a chance of flurries in the afternoon. Treeline temperatures around -8C. Winds NW 30-40 km/h at ridgetop.Thursday: 5-10 cm new snow expected. Freezing levels rising briefly to around 1300 m in the afternoon. Winds W 50-60 km/h at ridgetop.Friday: 2-5 cm new snow expected. Temperatures around -10C. Winds around 30 km/h from the NW.

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. These new windslabs cover older, stiff, dense wind slabs in exposed lee terrain at and above treeline. In the upper 80 cm of the snowpack a couple persistent weak layers exist, comprising of surface hoar and a facet/crust combo. This interface has produced variable results with snowpack tests, and operators are keeping a close eye on them as the load above increases and/or a slab develops.A bigger concern, especially in the Northern part of the region where the snowpack is thinner and more variable is weak faceted and depth hoar crystals combined with a crust from early October. This is now down around 80-120 cm. This deep persistent weakness appears to be more reactive in the north of the region. It is likely to be easier to trigger where the snowpack is relatively thin, and especially on steep, convex, north-facing slopes.

Avalanche Problems

Persistent Slabs

A weak layer buried around 50 cm from mid-December 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.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

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.
Parking, eating lunch, and regrouping in runout zones is bad practice.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

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.
Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3