Archived

Avalanche Forecast

Mar 26th, 2016–Mar 27th, 2016

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

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

Regions: Glacier.

There were a lot of skier triggered avalanches yesterday! Hazard can increase rapidly during sunny breaks. Remember that other groups may be above or below you & regroup in safe spots. Avoid slopes exposed to large cornices above when the sun is out.

Weather Forecast

Unsettled weather, with generally mild temps, is expected through the weekend. Today will be cloudy, but strong solar radiation is expected during sunny breaks. Sunday is expected to be cloudy, with flurries bringing ~5cm. Monday will be mostly sunny, with alpine temps reaching 0'C. Below treeline, mild temps will prevent an overnight recovery.

Snowpack Summary

~50cm of snow in the past 5 days, combined sustained SW winds, is building a storm slab that is up to 1m deep on lee slopes. This slab overlies a crust, which provides a good sliding surface, on all aspects. Mild temps and periods of strong solar are making it reactive. Avalanches may step down to multiple crusts in the top meter.

Avalanche Summary

There were lots of skier triggered avalanches yesterday. A size 3 was accidentally triggered on the "Thorington", NE aspect ~2700m. It was ~1m deep and ran ~1km on the crust. Several size 2's were also triggered, they were up to 40cm deep running up to 500m. A lower elevations wet slabs were triggered. Luckily no-one was involved in any of them!

Confidence

Timing or intensity of solar radiation is uncertain

Avalanche Problems

Storm Slabs

A touchy storm slab exists, with 30-50cm over a crust. On lee and cross-loaded features it's up to 1m deep. Yesterday skiers easily to triggered several size 2's and one size 3. They occurred in predictable places; steep slopes with a convexity.

Choose well supported terrain without convexities.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 3

Persistent Slabs

A series of crusts on solar aspects, buried up to 1.2 m deep, remain a concern. Tests generally take a hard force but continue to produce sudden planar results. This suggests that smaller avalanches, or cornice failures, may trigger large avalanches.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

There has not been an overnight freeze below tree-line for several days. Expect avalanches to be easy to trigger on steep slopes where moist snow overlies a crust. While unlikely to be large, avalanches will gain mass in gulleys and terrain traps.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2