Archived

Avalanche Forecast

Mar 15th, 2015–Mar 16th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

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

1: Low

The avalanche danger rating below treeline will be low

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: Glacier.

This is our first storm in quite sometime. The avalanche hazard has risen as a result of strong winds and new snow load.

Weather Forecast

The pineapple express that delivered rain and snow yesterday is being pushed south by a high pressure ridge. Freezing levels will hover around 1500m with lingering flurries today and mainly cloudy skies. Gradual clearing into Monday with more cooling as the ridge over our region strengthens. No precipitation is expected until mid next week.

Snowpack Summary

15-20cm of storm snow above 1900m. A mix of rain and snow (~15.0mm) below this elevation with a light dusting over a crust/moist snow. Storm winds peaked at over 130km/hr, wind slab at tree line and above will be a concern. Top 50cm has a few buried crusts that lay beneath previous wind slab which were reactive to human triggering.

Avalanche Summary

A natural cycle of moist/wet avalanches yesterday in the highway corridor. Avalanches were observed to size 2.5. This cycle continued into the evening as rain, snow and wind continued. Two days ago on Dome Glacier, a size 2.0 wind slab was triggered by the 5th skier on the slope, running 130m to the bench below the headwall.

Confidence

Due to the number of field observations

Avalanche Problems

Wind Slabs

Sustained strong to extreme overnight winds. Wind slabs were reactive to human triggering prior to this last storm.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid freshly wind loaded features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Storm Slabs

~20cm of dense storm snow at tree line and above. The first significant snowfall in quite some time overlies a variety of surfaces from crust, to facets to wind slab.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

A multitude of crusts are buried within the top meter of the snowpack. These may become reactive with the new load we received or with solar radiation. The bridging properties of near surface crusts weaken as the snowpack warms.

Be aware of the potential for large, deep avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3