Avalanche Forecast

Issued: Feb 25th, 2022 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada rbuhler, Avalanche Canada

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Lingering wind slabs may still be reactive to human-triggering in exposed terrain at higher elevations. 

In the east of the region, buried persistent weak layers may still be reactive to human-triggering in north-facing terrain around treeline. 

Summary

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

One more day under the influence of high pressure before the first in a series of storm systems arrives on Sunday. 

Friday Night: Mainly clear, light NW wind, treeline low around -15 °C. 

Saturday: Mainly sunny, light to moderate SW wind, treeline high around -5 °C. 

Sunday: Light snowfall 4-8 cm, moderate to strong SW wind, treeline high around -4 °C. 

Sunday night and Monday: Snowfall heavy at times, moderate to strong SW wind, treeline high around -1 °C. 

Avalanche Summary

On Thursday, four skier triggered avalanches were up to size 1.5 were reported on south and southeast aspects at treeline in the northwest of the region. Some small natural and human-triggered sluffing was also reported on steep slopes. 

Earlier in the week, several size 1-1.5 skier-triggered wind slabs were reported near ridge crests. Surface hoar layers buried in January have also been responsible for two recent size 2 avalanches in the east of the region. 

Snowpack Summary

20-30 cm of snow typically overlies a variable and potentially weak interface from mid-February which includes a melt-freeze crust, facets, and/or surface hoar. So far this interface has only been a concern in wind-loaded terrain where a slab has formed. In exposed terrain at higher elevations, recent strong northeast winds have caused extensive scouring and wind slab formation. Due to the northerly wind direction, reverse loading occurred meaning there may be wind slabs lingering in unusual places. 

Two layers of buried surface hoar sit in the upper snowpack which have been most reactive in sheltered areas at treeline. These are now down around 40-70 cm deep. While these layers had gone dormant in many parts of the region, they still remain reactive in snowpack tests in the east of the region and continue to be responsible for sporadic avalanches, including two avalanches earlier this week. 

The lower snowpack is well consolidated, with a crust/facet layer from early-December found around 100-200 cm deep. It is currently considered dormant, but could become active again later this season. Check out the forecaster blog for more information. 

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.

Problems

Wind Slabs

An icon showing Wind Slabs

Lingering wind slabs may remain reactive to human-triggering in exposed high elevation terrain. These may remain reactive for longer than normal where they overlie a firm crust. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

Surface hoar layers buried in January have been responsible for two recent size 2 avalanches in the east of the region. Various combinations of crusts above and below these layers have made the distribution and sensitivity of this problem difficult to pin down. 

Be cautious on northerly steep open slopes at and just below treeline where these layers are most likely to have been preserved and remain reactive.

Aspects: North, North East, East, North West.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 26th, 2022 4:00PM