Archived

Avalanche Forecast

Mar 28th, 2014–Mar 29th, 2014

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

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

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

A mixed forecast, with some new snow but possibly some sunny breaks, will make this weekend interesting. Even a bit of sun can pack a punch and rapidly increase danger.

Weather Forecast

A series of weather systems are expected to pass through the region over the weekend. Today should be mostly cloudy with flurries. Freezing levels may rise to 1500m, with alpine temps of -1. Light, but gusty SW winds are expected at ridgetop. Up to 10cm are expected by Sat morning. This pattern will continue through the weekend.

Snowpack Summary

On shaded and northerly aspects dry snow exists above 1500m. Soft wind loaded pockets may be forming with moderate SW winds. On solar aspects breakable sun crusts exist, and overlie a series of crusts in the top meter which react with hard planar results in tests. The Feb10 layer is down ~2m, shallower in thin areas, and continues to be a concern.

Avalanche Summary

Yesterday, skiers reported easily triggering small size 1-1.5 slabs, where the storm snow failed on convexities and unsupported slopes. On Wed, loose moist avalanches triggered by skiers when a bit of sunshine provided a lot of warmth. These avalanches ran fast and and far, into mature timber, with some growing to size 2.5.

Confidence

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

Avalanche Problems

Storm Slabs

20cm of new snow from earlier this week has bonded poorly to the snow below. It is especially reactive on solar aspects, where it is rapidly destabilized by even a little bit of sun. On lee aspects, soft slabs may exist from windloading by SW winds.

Start on small terrain and slope-cut the top of slopes before riding them.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Persistent Slabs

Weak layers from early March, now buried a meter deep, are still reactive in tests. They are most likely to be triggered on solar aspects where sun crusts exist. Smaller avalanches may step down to these layers, resulting in a big avalanche.

Choose well supported terrain without convexities.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Deep Persistent Slabs

A persistent weak layer from late Jan/early Feb remains a serious concern as it continues to be responsible for very large avalanches. This layer is variable in its distribution, is now buried up to 2m deep, is hard to trigger, and harder to predict.

Resist venturing out into complex terrain, even if you observe no obvious signs of unstable snow.Avoid convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 3 - 5