Avalanche Forecast

Issued: Jan 26th, 2015 8:24AM

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

triley, Avalanche Canada

Kootenay Boundary.

Strong solar radiation may result in large natural avalanches releasing down to a deeply buried weak layer.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Record warming on Monday should cool slightly on Tuesday as the ridge of high pressure begins to break down. Expect high overcast skies with periods of sunshine on Tuesday combined with moderate Southwest winds and freezing levels slowly descending from 3000 metres to around 2500 metres. High overcast is forecast for Wednesday with light winds and freezing levels around 1600 metres. The freezing levels should drop down to valley bottoms by Thursday morning. Expect valley cloud and a high overcast layer during the day on Thursday.

Avalanche Summary

Moist or wet loose snow avalanches have been reported from several areas up to size 2.0 over the past few days during the warming event. On Saturday a skier triggered a size 2 persistent slab which failed on the mid-December layer. This was a surprising result because it was on a well-supported, concave terrain feature (which had also been heavily skied).

Snowpack Summary

10-40 cm rapidly settling recent snow overlies various surfaces including surface hoar, a thin crust, or a settled slab. Warm temperatures are affecting the surface layers and turning them moist or wet. Warming may also change the persistent slab properties such that triggering is more likely. The mid-Jan surface hoar layer is down about 20-60 cm. These large, well-preserved surface hoar crystals sit on a thin crust up to about 1900m on north aspects and all the way to ridgeline on south aspects. A deeper crust/surface hoar combo buried in mid-December is typically down 80-120cm and has produced some large avalanches recently. With the unusually warm temperatures and known weak layers in the snowpack, it's a good time to do some investigative digging and venture gently.

Problems

Persistent Slabs

Persistent weak layers that were touchy during the recent storm may continue to be released by large additional loads, or by moist or wet avalanches in motion.

Avoid recently wind loaded features.>Choose well supported terrain without convexities.>Stick to small features with limited consequence.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

Moist or wet loose snow is expected to continue to release from light additional loads, or from strong solar radiation on Southerly aspects.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be aware of party members below you that may be exposed to your sluffs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Deep Persistent Slabs

Record breaking warm temperatures and extremely high freezing levels may result in deeply buried weak layers reacting to large loads like cornice falls or from light loads in thin snowpack areas.

Avoid common trigger points such as convexities, thin or variable snowpack areas and around rocks.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Jan 27th, 2015 2:00PM