Sea To Sky

A big storm means that an avalanche cycle is expected. Avoid avalanche terrain, including overhead hazard.

A complex snowpack has led to several recent avalanche incidents, including a fatal avalanche north of Pemberton, close to the Sea to Sky boundary. 

THURSDAY NIGHT - Snow, 20 cm / southwest wind, 30-50 km/h / alpine low temperature near -4 / freezing level 1000 m

FRIDAY - Snow, 30-40 cm with another 20 cm overnight / southwest wind, 40-60 km/h, gusting to 80 km/h / alpine high temperature near -1 / freezing level 1500 m

SATURDAY - Snow, 20-30 cm with another 30-50 cm overnight / southwest winds 60-80 km/hr / alpine high temperature near -2 / freezing level 1300 m

SUNDAY - Flurries, 10-15 cm / southwest wind, 20-30 km/h / alpine high temperature near -5 / freezing level 800 m

Avalanches are expected to be widespread on Friday.

At the time of publishing, there were a few reports of explosives triggered avalanches up to size 2.5. At least one of these failed on the persistent weak layer mentioned in the snowpack summary.

There was a fatal avalanche in the South Coast Inland region (near the Sea to Sky boundary) north of Pemberton in the Railroad Pass area on Monday that resulted in two fatalities. It was reported to be a size 2 persistent slab avalanche on a west aspect, around 1650 m. The RCMP press release can be viewed here, and the Avalanche Canada report can be found here.  

A size 2.5 avalanche was triggered on Monday by a skier on Rainbow Mountain, which resulted in a full burial and, thankfully, a successful rescue. The avalanche failed on a 60 cm deep crust and facet layer on a northeast aspect around 1800 m. 

A natural size 3 persistent slab avalanche was reported on Mount MacBeth on Monday, check out this MIN report for details of this observation.

These avalanches highlight the ongoing potential to trigger persistent weak layers in the snowpack. 

With 20 cm of new snow expected on Thursday night and another 30-40 cm in the forecast for Friday, storm slabs will be widespread.

This new snow will bring recent storm snow totals to over 100 cm.

The snowpack is currently complex, and two concerning weak layers may be present in the snowpack: 

• The shallower layer, around 60 to 100 cm deep, includes feathery surface hoar crystals. This layer may be found in sheltered terrain features at treeline and lower alpine elevations, but has been reported as spotty across the region. 
• The more widespread weak layer includes sugary faceted grains that sit on top of a hard melt-freeze crust. This layer ranges in depth from 20 cm to 120 cm due to the wind scouring and loading the snow in different terrain features over the past two weeks. The layer has been reported as being widespread up to around 2000 to 2200 m. 

There have been several recent human triggered avalanches on these layers. 

The remainder of the snowpack is well-settled.

• Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
• Avoid areas with overhead hazard.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.