Avalanche Forecast

Issued: Jan 28th, 2015 8:19AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Deep Persistent Slabs.

Avalanche Canada esharp, Avalanche Canada

Conditions change with elevation. Avalanche problems are lingering in the alpine while a widespread melt-freeze crust will make for challenging riding at lower elevations.

Summary

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

A ridge of high pressure will prevail through until Saturday over the southern half of BC, leading to mainly sunny skies in the mountains with extensive low cloud in the valleys. The north of the region may see some light precipitation on Friday as a front moves over the north of the province. Winds will be light through the forecast period.

Avalanche Summary

As the temperature drops I expect that avalanche activity will continue to slow down. The recent snow, rain, and wind were a great test of buried persistent weaknesses in the snowpack and resulted in a widespread avalanche cycle. The mid-January surface hoar layer was responsible for the majority of the recent avalanche activity in the region, producing numerous avalanches up to size 3.5. Reactive wind slabs may be lingering in the alpine and could produce large avalanches where they sit above the surface hoar.

Snowpack Summary

In the north of the region up to 10 cm of new snow sits on a variety of old surfaces. A melt freeze crust can be found at or just below the surface up to around 2000m. I suspect that the crust is breakable at treeline and becomes thicker and more supportive at lower elevations. Strong southwesterly winds redistributed snow in the alpine forming windslabs in lee features. The mid-January surface hoar layer remains a concern and can be found down between 40 and 80 cm. I suspect that this layer may have been destroyed by moist/wet snow bellow treeline. The midpack is broken by the mid-December surface hoar layer 80 to 140cm below the surface. This layer appears to be slowly gaining strength.

Problems

Persistent Slabs

An icon showing Persistent Slabs
At upper elevations a layer of surface hoar sitting on a crust buried 40 to 80 cm down may still be capable of producing large avalanches especially in wind loaded features.
Caution around convexities or areas with a thin or variable snowpack.>Be careful with wind loaded pockets>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
A deeper layer of surface hoar is still capable of producing large avalanches given a large enough trigger in the right spot. It is especially a concern on open slopes around treeline.
Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Jan 29th, 2015 2:00PM

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