Avalanche Forecast

Issued: Dec 24th, 2013 8:37AM

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

Avalanche Canada swerner, Avalanche Canada

If heavier snow accumulations are observed by lunch time, consider the Danger Ratings to be one step higher.

Summary

Confidence

Poor - Timing of incoming weather systems is uncertain on Wednesday

Weather Forecast

It looks like the Interior Mountains will see snow for Christmas, as a stream of moisture spreads from North South Wednesday afternoon and overnight into Thursday. I'm uncertain with timing, however most model runs are agreeing with precipitation amounts.Christmas Day: Snow amounts 5-10 cm. Alpine temperatures -4. Ridgetop winds moderate from the South.Thursday: Snow amounts 15-20 cm. Alpine temperatures -7. Ridgetop winds light-moderate from the South. Freezing levels rising to 1300 m. Friday: Snow amounts tapering off up to 5 cm. Alpine temperatures near -4. Freezing levels 1000 m. Special Notice: Our radar has just picked-up what appears to be a flying sleigh. Our forecasters believe the sleigh belongs to Santa as it is being pulled by at least 8 reindeer. The sleigh is now in the far north of the province at the 2000m elevation and is currently headed south. More information will be posted as it becomes available.

Avalanche Summary

On Monday, storm slab avalanche activity up to size 2 was observed on most aspects from 1500 m and up. Most avalanches failed down 20 cm, and were said to be touchy with wide propagations on the most recently buried surface hoar layer. With more snow, wind and warming avalanche danger will be on the rise.

Snowpack Summary

Recent winds from the NW have built pockets of new wind slab on opposite slopes. Up to 40 cm of new snow sits on a surface hoar/ stellar / crust layer buried approximately 20 cm down, and has been very touchy to rider triggers. The new storm snow is settling quickly, however storm slabs have been more reactive where there has been wind effect. Buried down 70 cm is the early December surface hoar, facetted snow, and/or a crust interface. Lately this has been more stubborn to rider triggers. The average snowpack depths at treeline range from 100 cm -150 cm.Digging deeper 70-90 cm is the late-November layer, which consists of a sun crust/ facet combo on steep south facing slopes and larger, proud surface hoar crystals in sheltered areas at lower elevations. This layer is generally considered to be unreactive. However, professionals are keeping a close eye on it.At the base of the snowpack the October crust is most predominant on north-facing alpine slopes with smooth ground cover. Triggering this weakness is unlikely, but if triggered the resulting avalanche would be very large and consequential.

Problems

Storm Slabs

An icon showing Storm Slabs
New storm snow may be touchy and reactive, especially in wind affected areas. Natural avalanche activity is expected. Further loading and smaller avalanches may trigger buried weak layers and initiate large- very large avalanches.
Choose conservative lines and stick to supportive, low angle terrain.>The new snow will require several days to settle and stabilize.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Persistent weak layers of facets, surface hoar, and/or a crust exist in the upper 90 cm of the snowpack. With more load they may be susceptible to triggering, creating large - very large destructive avalanches.
Avoid convexities or areas with a thin or variable snowpack. Thin areas may propagate to deeper instabilities.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Dec 25th, 2013 2:00PM