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Archived

Avalanche Forecast

Jan 10th, 2013–Jan 11th, 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
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

Regions: Glacier.

With clearing skies in the forecast, be cautious of heading out into big terrain too quickly.  A persistent weak layer is still problematic, and skier triggering remains likely.  Don't forget about deep tree wells and cornices.

Weather Forecast

An arctic front will push through the Columbia's today bringing cooler temperatures.  A ridge will build behind this, providing clearing skies for later in the day and into the weekend.  Patchy snow flurries are still possible, but very little snow accumulation is expected.

Snowpack Summary

Up to 70 cm of storm snow overlies a weak layer of buried surface hoar and facets. This layer is best developed between 1500 and 2000 meters, but exists at all elevations.  This layer is also best developed on the eastern side of the park, where surface hoar grew larger than in the west.  This variability will make hazard evaluation tricky.

Avalanche Summary

Avalanche control yesterday produced many avalanches, mostly in the size 2-2.5 range.  These avalanches primarily involved storm snow.  We have had limited observations In the backcountry, however a widespread natural cycle is suspected.  Natural avalanche activity will likely subside today, but human triggering is still likely.

Confidence

Due to the number of field observations

Avalanche Problems

Storm Slabs

Up to 70 cm of storm snow lies on a weak interface of surface hoar and sun crust, burried on January 4.  Avalanche control yesterday produced many avalanches on this layer.  Storm snow will continue to be reactive to skier triggering
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3

Persistent Slabs

The January 4 surface hoar, sun crust, facet interface will likely become a persistent weak layer in the weeks to come.  Recent strong winds have already created harder wind slabs at and above treeline on this layer.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3