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Archived

Avalanche Forecast

Jan 21st, 2016–Jan 22nd, 2016
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
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: Northwest Coastal.

Conditions remain primed for both natural and human triggered avalanches. Avalanches can be triggered in lower angle terrain and have the potential to propagate very widely.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Friday: Cloudy with 5-10 cm of new snow. The freezing level is near 600-800 m and winds are moderate from the SW. Saturday: Mainly cloudy with sunny breaks and a chance of flurries. The freezing level is near 600 m and winds ease to light. Sunday: Mainly cloudy with a chance of flurries. The freezing level is around 400 m and winds are moderate from the southeast.

Avalanche Summary

Explosives control in areas near Bear Pass and northeast of Terrace produced numerous slab avalanches, size 2-3.5, likely failing on the January 9th interface. Some had very impressive propagations. Other areas reported small skier triggered size 1 slabs and some remotely triggered slabs. Thursday's weather may not have been enough to tip off a widespread natural avalanche cycle. Rider triggering and triggering from a distance remain a concern. The size and likelihood of avalanches will be on the rise as the slab continues to develop with more snow, wind, and milder temperatures.

Snowpack Summary

Thursday's weather affected the Northern part of the region more with some areas receiving up to 20 cm of new snow. Southern sections saw less snow (around 5 cm), but moderate-strong S-SE winds and milder temperatures were common throughout the region. This puts the January 9th surface hoar/facet layer down 50-70 cm in most places. Approximately 10 cm below this weakness you might find the Dec. 26/31 surface hoar layer. Reports of remote triggering, whumpfing, and sudden "pops" shears are all indications that both these layers could propagate well if triggered. Deeper persistent weaknesses buried in December have the potential to wake-up to heavy loading, rapid warming, or avalanches stepping-down.

Avalanche Problems

Storm Slabs

Storm slabs continue to grow with continued light to moderate snowfall on Friday. Expect deep and touchy slabs in lee (NE-NW) and cross-loaded terrain.
Be cautious as you transition into wind affected terrain.>Stick to non-avalanche terrain or small features with limited consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4

Persistent Slabs

In many places, loading on the buried surface hoar layers has been incremental. This could make the problem trickier and will require discipline and conservative terrain choices. Other areas may have had enough load to tip off a natural cycle.
Be careful with low angle slopes that may not normally be a concern.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 6