Archived

Avalanche Forecast

Mar 31st, 2017–Apr 1st, 2017

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Warm, wet, and windy conditions are expected to increase the avalanche danger to HIGH.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Overnight: 10-20 cm of new snow above 600 metres combined with moderate gusty southwest winds. Saturday: 10-15 cm during the day with moderate westerly winds and daytime freezing up to 1100 metres. Sunday: Light west winds with flurries or periods of light snow and freezing levels around 1000 metres. Monday: Broken skies with a chance of clearing in the afternoon.

Avalanche Summary

One natural ice fall and one natural cornice fall size 3.0 were reported from the Bear Pass area on Thursday. Numerous natural storm slabs up to size 2.0 were reported on Wednesday. I suspect that new storm slabs will develop overnight due to the forecast new snow and wind.

Snowpack Summary

Storm slabs continue to develop in the alpine and at treeline. Warm daytime temperatures have created moist snow at treeline and wet snow below treeline. The February 21st persistent weak layer continues to be a concern for triggering large avalanches. This combination of crust and weak facets is now down 100-150 cm, and may be triggered by light additional loads in shallow weak spots adjacent to large terrain features. The snow below treeline may become weak and release as loose wet avalanches or wet slabs in steep unsupported terrain features.

Avalanche Problems

Storm Slabs

Forecast new snow and wind are expected to develop or add to existing storm slabs overnight.

If triggered, the storm slabs may step down to deeper layers resulting in large avalanches.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

A weak facet/crust layer from late February has produced several large human triggered avalanches the past few days. Triggering this layer is most likely in shallower areas, but a storm slab or cornice fall could act as a trigger.

Remote triggering is a concern, watch out for adjacent slopes.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

Loose wet avalanches may release naturally at lower elevations due to warm daytime temperatures, new snow or rain, and high freezing levels.

Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 2