Avalog Join
Archived

Avalanche Forecast

Jan 8th, 2013–Jan 9th, 2013
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
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
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: South Coast.

Confidence

Good

Weather Forecast

Wednesday: Snow flurries with another 5-10cm possible, moderate southwesterly winds becoming northwesterlies in the afternoon, and freezing levels are expected to rise as high as 1500m on Tuesday night but drop back down to 700m by midday Wednesday. Thursday and Friday: Mainly sunny and dry with light northerly winds and freezing levels in valley bottoms.

Avalanche Summary

Reports from the Coquihalla area on Monday include several natural avalanches up to Size 2 as well as several 20cm thick Size 1 ski-cut slab avalanches on small terrain features. A thin, but relatively wide-propagating avalanche was triggered on Needle Peak in the Coquihalla area on Sunday. You can read the description here. This kind of avalanche is likely to increase in size and destructive potential with additional loading by new snow and wind.

Snowpack Summary

Another 30cm in the Coquihalla area since late Monday brings the storm snow total to over 60cm since Friday, while the Duffey Lake area got around half that much. Weaknesses exist within this recent storm snow as well as at the interface with the previous snow surface, which includes large surface hoar, facets, old hard wind slabs, or a sun crust. Recent compression tests on a north aspect below treeline gave easy sudden planar shears down 23cm, moderate sudden planar shears down 39cm, and hard sudden planar shears down 60cm. No significant weaknesses have been reported recently below this in the mid snowpack layers. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in steep, shallow, rocky terrain where more facetting has taken place.

Avalanche Problems

Storm Slabs

The new snow has set up touchy slab conditions in many areas, especially where strong southerly winds have created thicker and denser deposits. The Coquihalla area is particularly dangerous with significantly higher amounts of recent storm snow.
Stick to simple terrain and be aware of what is above you at all times.>Be cautious as you transition into wind affected terrain.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5