Northwest Coastal

Make conservative terrain choices and be patient as you gather information after the storm. Snow, rain, wind, and warmth have quickly changed the snowpack.

Sunday Night: Cloudy. 2-10 cm of snow expected. Strong southwest wind, trending to extreme at higher elevations. Freezing level around 1000 m.

Monday: Partly cloudy, clearing through the day. Possible trace of snow expected. Moderate west wind, trending to extreme at higher elevations, generally light by the afternoon. Freezing level falling to around 500 m.

Tuesday: Scattered clouds. No new snow expected. Light variable winds. Freezing level at valley bottom. Treeline high around -7 °C.

Wednesday: Cloudy. 5-20 cm of snow expected. Strong south wind trending to southwest at higher elevations. Freezing level rising to 500 m. 

Saturday:

-Northwest of Terrace, a professional operation reported a very large, naturally triggered avalanche that started as a storm slab, and stepped down to a deeper, persistent crust layer. The crown was an average of 1 m deep, and 2.2 m at the deepest. It was on a north aspect at 1800 m. It was 500 m wide and ran for 500 m.

 -Northeast of Kitimat, several wet loose avalanches up to size 2 were reported above treeline. Riding conditions did not sound great. Check out the Mountain Information Network post here for more details. 

-A widespread natural avalanche cycle took place around the region. Professional operations reported numerous large, naturally triggered wet loose avalanches at treeline and below, as well as storm slab or loose dry avalanches at treeline and above. The largest reported were size 3, in the Bear Pass area.

If you are getting out in the backcountry, and have conditions information, or even just good vibes and good photos to share, consider making a post on the Mountain Information Network (MIN). 

Snowfall tapers off by Monday morning, bringing storm totals up to 50-90 cm, but strong southwest through west wind continue to blow. Expect to find deeper and more reactive slabs on north through east facing lee features. 

Due to fluctuating freezing levels, riding conditions could be tricky around treeline and below. You may find a hard or breakable crust, or dense, grabby snow. This may sit on top of less dense snow, making the upper snowpack a little upside down.

In areas around Stewart, Bear Pass, and further north, a layer of facets or surface hoar can be found about a meter below the snow surface. Avalanches have been sliding on this weak layer through the recent storm, but it may strengthen as the temperatures cool and the snowpack adjusts to the new load.

Check out this Mountain Information Network post for good picture of conditions in the Shames backcountry on Saturday. 

The early December rain crust is up to 10 cm thick, down 100-200 cm in the snowpack, and exists to an average of 1400 m in elevation. While this layer had generally gone dormant in the region through the cold period, we're still waiting for reports to come in on how it reacted to the heavy snow and rain through the weekend. 

Extra caution is necessary while the snowpack undergoes substantial warming after a prolonged period of cold conditions. 

• Keep in mind that human triggering potential persists as natural avalanching tapers off.
• Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
• Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Avoid steep convexities or areas with a thin, rocky, or variable snowpack.