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Archived

Avalanche Forecast

Jan 22nd, 2016–Jan 23rd, 2016
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
1: Low
The avalanche danger rating below treeline will be low
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
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast.

Danger could be LOW below treeline in the Cascades where heavy rain saturated the snowpack and has probably refrozen into a solid crust.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Saturday: Cloudy with sunny breaks. The freezing level is around 600 m and winds are light from the W-SW. Sunday: Cloudy with sunny breaks and a chance of flurries. The freezing level is at 500 m and winds are light from the S-SW. Monday: Cloudy with sunny breaks and a chance of flurries. The freezing level remains near 500 m and winds rise to moderate from the S-SW.

Avalanche Summary

Observations were quite limited during the storm on Thursday; however, a large and widespread avalanche cycle was very likely in most places. In the Coquihalla, a widespread cycle was observed with most avalanches being size 2-2.5 at treeline and in the alpine. At least one size 3 was reported with very impressive propagation. To the north (Upper Lillooet River), a widespread cycle was reported below treeline with avalanches up to size 2.5 being observed. I suspect we will hear more about this cycle in the next day or two.

Snowpack Summary

So far, 30-50 cm of new snow has fallen since Wednesday night. The snow line may have gone up to ridge top in the south, but only 1400-1600 m in the north. Expect dense new wind and storm slabs, and fresh cornice growth at upper elevations. Heavy loading from snow and rain, and the resulting avalanche cycle, may have flushed-out the mid- and early-January surface hoar/facet layers that were initially buried 30-50 cm deep. However, don't rule these layers out right away. It may still be possible to trigger shallow slopes that did not release naturally. The mid and lower snowpack is generally strong, with the exception of shallower snowpack areas that may be more faceted.

Avalanche Problems

Storm Slabs

Heavy snow continued in parts of the region on Friday helping create deep slabs at higher elevations, especially in immediate lee and cross-loaded terrain. 
Avoid freshly wind loaded features.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

This problem may still be found in places that did not see widespread avalanche activity. Be particularly caution in the northern part of the region between 1500 and 1900 m elevation. 
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Be wary of slopes that did not previously avalanche - even on low angle terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 5