Avalanche Forecast

Issued: Feb 22nd, 2018 4:26PM

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

Avalanche Canada mconlan, Avalanche Canada

Wind slabs linger in lee features at higher elevations. Watch for signs of avalanche activity and locally unstable snow, such as whumpfing and shooting cracks.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

FRIDAY: Increasing cloudiness with snowfall beginning late afternoon, accumulation 2 to 5 cm, moderate to strong southwesterly winds, alpine temperature -14 C, freezing level below valley bottom.SATURDAY: Early-morning snowfall then clearing to partly cloudy, accumulation 5 cm, light to moderate northwesterly winds, alpine temperature -11 C, freezing level near 500 m.SUNDAY: Cloudy with light snowfall, accumulation 5 to 15 cm, moderate to strong westerly winds, alpine temperature -9 C, freezing level near 800 m.

Avalanche Summary

On Wednesday, a few small slabs (size 1) were triggered by skiers on southerly to easterly slopes between 1600 and 2100 m.  They were 30 cm deep in steep and wind-loaded terrain.  Sluffing was also noted in steep terrain.

Snowpack Summary

Highly variable snow surfaces exist, including wind-pressed snow (from primarily northeast winds), stiff wind slabs, sun crusts on steep solar aspects, and 30-50 cm of low density snow in sheltered areas at teeline and below.  A crust layer can be found beneath the storm snow on sun-exposed slopes and below 1800 m.Weak layers that formed in January and December are gradually gaining strength. The layers include several surface hoar and facet layers buried 1-2 m below the surface and a crust/ facet interface near the base of the snowpack. No avalanches have been reported on these layers for the past two weeks and snowpack tests are showing improved bonding. Despite these signs, avalanche professionals are still treating these layers with respect and being cautious around shallow start zones and in big avalanche paths.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds from various directions have redistributed 30-50 cm of recent snow into stiff wind slabs at all elevations.  Wind slabs have been reactive to human triggers.
If triggered, wind slabs may step down to deeper layers, resulting in large avalanches.Approach lee and cross-loaded slopes with caution.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Feb 23rd, 2018 2:00PM