Avalanche Forecast

Issued: Apr 11th, 2017 3:32PM

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

mgrist, Avalanche Canada

Northwest Coastal.

Strong easterly winds on Tuesday-Wednesday may result in unusual snow loading patterns. Cornices are large and remain a significant concern.

Summary

Confidence

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

Weather Forecast

Light precipitation and STRONG easterly winds on Tuesday-Wednesday. Unsettled weather and cool temperatures thereafter. WEDNESDAY: Mix of sun and cloud with isolated flurries (0-5cm). Strong easterly ridgetop winds. Freezing level around 1500 m.THURSDAY: Mainly cloudy with isolated flurries (2-5cm). Moderate southeasterly ridgetop winds. Freezing level around 1400 m.FRIDAY: Cloudy with scattered flurries (3-5cm). Light southerly ridgetop winds. Freezing level around 1300 m.

Avalanche Summary

On Monday, several loose wet avalanches to Size 2.5 were reported in the afternoon with solar input. In the north of the region a cornice failure on a northwest aspect resulted in a slab avalanche, Size 3.0.

Snowpack Summary

Small amounts of new snow (up to 10cm) fell at higher elevations in the past few days with light to moderate southerly winds. The new snow will likely be sitting on hard surfaces created by strong winds last week, or melt-freeze crusts below 1400m.Sunny breaks and warmer temperatures on Sunday & Monday has likely left a supportive temperature crust on all aspects up to treeline. North facing alpine slopes reportedly have up to 10cm dry powder, on a firm crust. A weak layer of facets and crusts from late February are buried 100-120 cm down. The layer has been unreactive recently and has a variable distribution. That said, rapid warming of the snowpack or a large trigger, such as a cornice, may still have the potential to trigger it.

Problems

Wind Slabs

Small amounts of new snow and moderate to strong east winds may result in unusual loading patterns in lee features below ridgetops.

Approach steep lee and cross-loaded slopes with caution.Use ridges or ribs to avoid pockets of wind loaded snow.Avoid freshly wind loaded features.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Large cornices may become weak with daytime warming and have the potential to trigger slabs on the slopes below.

Even small cornice falls may trigger larger avalanches.Avoid steep slopes below cornices.Give cornices a wide berth when traveling on ridges.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 12th, 2017 2:00PM