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Archived

Avalanche Forecast

Dec 25th, 2014–Dec 26th, 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
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
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
2: Moderate
The avalanche danger rating in the alpine will be moderate
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.

A special avalanche warning has been issued that includes the South Coast Inland.  A buried surface hoar layer in the south of the region remains reactive and may persist for longer than usual. For further details see: http://goo.gl/JDfMjZ

Confidence

Fair - Due to the number of field observations

Weather Forecast

A ridge of high pressure should keep the South Coast dry and mostly sunny on Friday. Freezing levels are expected to reach around 800m with light NW winds in the alpine. The next storm system is expected to reach the South Coast on Friday night. 5-10mm of precipitation are expected on Saturday with freezing levels reaching around 600m and light-to-moderate NW winds in the alpine. Sunday should be a mix of sun and cloud with freezing levels around 500m.

Avalanche Summary

We haven't received any reports in a few days.  If you are out in the mountains, please consider sending us your observations or posting on our website. On Monday we received a report of storm slabs up to size 2.5 being remote-triggering from flat areas up to 75m away in the Coquihalla area between 1600 and 1900m elevation. Slabs were 40-70cm thick and were releasing on the surface hoar layer. Natural activity is not expected on Friday but human triggering remains possible.

Snowpack Summary

A persistent slab sits above the touchy mid-December surface hoar layer. In the north of the region the slab is around 30-40cm thick and in the south it is 50-80cm. The surface hoar appears to be quite reactive at treeline and possibly into the lower parts to the alpine, especially where it was sheltered from wind. Reports suggest that it is most reactive in the Coquihalla and Allison Pass areas. About 10cm below the surface hoar layer is a thick rain crust the extends to around ridgetop elevation. Strong SW winds have created wind slabs in exposed alpine terrain which may still be a concern.

Avalanche Problems

Persistent Slabs

A buried surface hoar layer remains a concern, especially in the southern parts of the region.  This layer appears to be most reactive on north facing slopes around treeline elevation.
Avoid open slopes and convex rolls where buried surface hoar may be preserved.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3