Avalanche Forecast

Issued: Nov 27th, 2021 4:00PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Loose Wet.

Avalanche Canada dboucher, Avalanche Canada

Please respect all restrictions on BC highways.

Wet snow at higher elevations will increase the load to the snowpack and is likely to trigger recent snow above a weak layer. 

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

The bulk of the precipitation with he ongoing storm will fall overnight Saturday, most likely as rain everywhere except maybe the high alpine in the north of the region.

Saturday night: Rain or wet snow mixed with rain; 20-40 mm. Strong to extreme southwest winds. Alpine low temperatures around zero with freezing levels at 2200 metres in the north and 2800 metres in the south.

Sunday: Periods of wet snow mixed with rain; 15-20 cm. Strong southwest winds. Alpine high temperatures around zero with freezing levels at 2000 metres.

Monday: Cloudy with scattered flurries. Moderate southwest winds. Alpine high temperatures -3 C with freezing levels at 1800 metres.

Tuesday: Cloudy with scattered flurries. Strong southwest winds. Alpine high temperatures around zero with freezing levels at 1700 metres.

Avalanche Summary

Natural and explosive triggered to size 2, running on buried crusts and to ground, have been observed below treeline elevation. In addition, neighboring Sea to Sky region reported large avalanches sliding on recently buried surface hoar and deeper buried crusts. If a similar avalanche cycle has not already occurred at upper elevations in the inland region, further loading by subsequent storms, warming temperatures or human triggers could initiate avalanche activity on these layers.

Reports in the region remain limited. Be sure to post your observations to the Mountain Information Network !

Snowpack Summary

A series of incoming storm systems will bring plenty of precipitation. However, due to high freezing levels, most of the precipitation will likely fall as rain except maybe the high alpine in the north of the region.

All this rain and wet snow will fall over 25-40 cm of recent snow that may sit over a layer of crust or surface hoar. In lee terrain features, thicker wind slab are likely to be found.

Deeper in the snowpack, a hard rain crust sits around 40-60 cm below the surface, or shallower on windward slopes. Another rain crust exists near the bottom of the snowpack. Recent avalanche activity has been observed on these layers.

Average snowpack depths in the alpine are now 100-150 cm. Below treeline, depths of 30-40 cm have been reported around 500 m, decreasing dramatically with elevation, and still below threshold for avalanching in many areas.

Early season hazards such as rocks, stumps, and creeks are a concern below the alpine.

Terrain and Travel

  • Investigate the bond of the recent snow
  • Avoid exposure to overhead avalanche terrain during periods of heavy loading from new snow, wind or rain.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
  • Even a small avalanche can be harmful if it pushes you into an obstacle or a terrain trap.

Problems

Storm Slabs

An icon showing Storm Slabs

Wet snow at higher elevations will increase the load to the snowpack. As a result, storm slab avalanches are likely in recent snow above a weak layer of surface hoar and/or a crust buried down 25 to 40 cm.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet

Heavy rain at lower elevation will likely weaken surface snow. As a result, expect wet loose avalanches to run on steep terrain. 

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Nov 28th, 2021 4:00PM