Avalanche Forecast

Issued: Nov 26th, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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Please respect all restrictions on BC highways.

Recent snow may remain reactive where it sits over a weak layer. If you are increasing your exposure to avalanche terrain, do so gradually as you gather information. 

Summary

Confidence

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

Weather Forecast

The next storm will start to trickle into the region over the day Saturday, accompanied by rising freezing levels. The bulk of the precip will fall overnight Saturday, most likely as rain everywhere but the high alpine in the north of the region.

Friday night: Partly cloudy. Light southwest winds. Alpine low temperatures around -6. Freezing level 1000 m.

Saturday: Flurries starting in the afternoon, with 10-15 mm overnight. Moderate to strong southwest winds, increasing over the day. Alpine temperatures reaching 0 C by evening. Freezing levels rising as high as 2200 m in the north and 2800 m in the south.

Sunday: 10-15 cm wet snow or rain. Moderate to strong southwest winds. Alpine temperatures around 0C. Freezing levels dropping down below 2000 m.

Monday: Clearing. Light wind. Alpine temperatures around -3 C. Freezing levels around 1300 m.

Avalanche Summary

Roadside (below treeline elevation) observations from near Pemberton include natural avalanches to size 1.5 and explosive triggered to size 2, running on buried crusts and to ground. We have received no reports from alpine or treeline elevations.

Thursday and Friday in the neighboring Sea to Sky region (which received greater snowfall amounts this week) large avalanches were observed 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. If you go out in the mountains, please post your observations and/or photos to the Mountain Information Network!

Snowpack Summary

25-40 cm of recent snow may sit over a layer of crust or surface hoar. Strong winds have likely loaded recent snow into thicker slabs in lee terrain features.

A hard rain crust now 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 120-160 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.

Terrain and Travel

  • Investigate the bond of the recent snow
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.

Problems

Storm Slabs

An icon showing Storm Slabs

A weak layer of surface hoar and/or a crust was buried by the previous storm and it may prolong the reactivity of recent snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Nov 27th, 2021 4:00PM

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