Avalanche Forecast

Issued: Feb 19th, 2018 4:19PM

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

Avalanche Canada mconlan, Avalanche Canada

Strong outflow winds have created touchy wind slabs that are likely easy to trigger. Watch out on solar aspects where the sun could weaken the snow surface.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY: Sunny, light to moderate northerly winds, alpine temperature near -12 C, freezing level below valley bottom.WEDNESDAY: Partly cloudy, moderate to strong northerly winds, alpine temperature near -10 C, freezing level below valley bottom.THURSDAY: Partly cloudy, light to moderate westerly winds, alpine temperature -9 C, freezing level below valley bottom.

Avalanche Summary

Many small to large (size 1 to 3.5) wind slabs were reported on both Saturday and Sunday in lee features and cross-loaded terrain on southerly to easterly slopes. The avalanches were triggered naturally and by skiers.Avalanche activity may slow down with a period of cold, clear weather expected to persist well into the week, unless the sun is powerful enough to warm the snow surface. Watch for steep sunny slopes due to the suns influence, lee features for reactive wind slabs, and be extra cautious near thin spots and shallow snow pack areas where triggering a deeper weak layer is more likely.

Snowpack Summary

Northeasterly winds have created stiff wind slabs on leeward slopes and scoured wind-exposed slopes at all elevations.Deeper in the snowpack, two layers of crust and/or weak surface hoar are 20 to 40 cm deep and 60 to 100 cm deep. The deeper crust exists well into the alpine and the surface hoar can be found in sheltered areas in lower alpine and tree line elevations. Snowpack tests have produced hard, sudden results on weak, sugary snow crystals associated with this deeper crust in the Smithers area, suggesting that it is a layer of concern.

Problems

Wind Slabs

An icon showing Wind Slabs
Strong winds have produced stiff and touchy wind slabs in lee and cross-loaded features. The slabs have been described as highly variable.  They will likely be reactive to human triggers.
If triggered, wind slabs may step down to deeper layers, resulting in large avalanches.Use ridges or ribs to avoid pockets of wind-loaded snow.Be cautious as you transition into wind-affected terrain; avoid lee and cross-loaded features

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
Several weak layers are lurking in our snowpack. They will be more easily triggered where the snowpack is shallow.
Minimize overhead exposure, as avalanches could run for long distances.Be aware of the potential for wide propagation.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3.5

Valid until: Feb 20th, 2018 2:00PM