Avalanche Forecast

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

  

FRIDAY NIGHT: Snow; 5-10 cm. / Strong, southwest ridgetop wind / alpine low temperature -9 / Freezing level 1000 m.

SATURDAY: Snow; 5-10 cm. / Strong, southwest ridgetop wind / alpine high temperature -5 / Freezing level 1400 m.

SUNDAY: Snow; 5-15 cm. / Strong, southwest ridgetop wind / alpine high temperature -4 / Freezing level 1500 m.

MONDAY: Cloudy with flurries; 3-5 cm. / Moderate, west ridgetop wind / alpine high temperature -7 / Freezing level 1200 m.

On Thursday, a ski cut resulted in a size 2 persistent slab avalanche on a northeast aspect in the alpine near Kicking Horse Mountain Resort. MIN report HERE.

A skier triggered avalanche was reported in the Golden area on Wednesday. Check out the MIN report HERE. The 50 cm failure plane depth matches up with the persistent weak layers discussed in our snowpack summary. The report also suggests that in some areas more recent wind slabs may be quite reactive.

These recent avalanches are a reminder that when persistent slabs are the problem; conservative terrain choices are the answer.

A skiff of new snow has buried a new layer of surface hoar in many parts of the region. This will be a key interface to watch as new snow piles up over the weekend.

Also at the surface, winds blowing from a variety of directions last week formed wind slabs in lee features at treeline and above.

There are currently several critical layers of concern. The early December surface hoar is down 30 to 80 cm. It has recently been sensitive to remote triggering which is well illustrated in this MIN post from the Golden area.

Below, or near the surface hoar you may encounter a crust. This crust has been observed as high as 2400 m. in the south of the region and 1800 m. in the north.  

The lower snowpack is characterized by more crusts, the most notable is a rain crust from early November that is 50 to 130 cm deep. This crust is sitting near the base of the snowpack, surrounded by a weak layer of sugary facets. It is most likely to be reactive to human triggers in steep, shallow, rocky areas with a thin to thick snowpack.

• Uncertainty is best managed through conservative terrain choices at this time.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Remote triggering is a concern, watch out for adjacent and overhead slopes.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.