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Archived

Avalanche Forecast

Feb 4th, 2016–Feb 5th, 2016
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

Snow, wind, and rising freezing levels will increase the avalanche danger. Deeply buried persistent weak layers may be triggered by the increased load from the storm. Patience and a conservative approach to terrain are recommended.

Confidence

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

Weather Forecast

5-10 cm overnight with extreme southwest winds and freezing levels at or just above valley bottoms. Another 5-10 cm during the day on Friday with strong southwest winds and freezing levels spiking up to about 1000 metres. Light snow combined with moderate southerly winds and dropping freezing levels on Saturday. On Sunday, continued light snow with increasing southerly winds and rising freezing levels.

Avalanche Summary

On Wednesday there was a report of an accidentally triggered size 1.0 avalanche on a short steep roll below treeline at 1500 metres in the Ashman area. The crown was 30-50 cm deep and 25 metres wide; compression tests on this layer produced easy-moderate sudden shears. Some loose dry avalanches up to size 1.0 were reported from the Hankin area on Tuesday in the alpine on steep east aspects.

Snowpack Summary

5-10 cm of new snow may be sitting on a layer of surface hoar that was buried in the last few days. Moderate southeast winds have developed new wind slabs in the alpine and at treeline, and forecast snow and southwest winds are expected to build new storm slabs on all aspects. Below 1200-1400 m the new snow probably sits on a crust. Fresh soft wind slabs are likely in exposed lee terrain. The early or mid January surface hoar layer is reported throughout the region and is generally 30-50 cm deep. Observers have found this persistent weakness on all aspects and at all elevations. It consistently produces moderate "pops" results in snowpack tests. Below this, the Boxing Day surface hoar problem may also be lurking. The mid and lower snowpack is generally quite weak and faceted, especially in lower snowpack areas.

Avalanche Problems

Storm Slabs

New storm slabs developing rapidly with forecast new snow and strong winds. Pockets of wind transported snow may be deep and easily triggered.
Minimize exposure during periods of heavy loading from new snow, wind.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

New snow has been slowly accumulating over a layer of facets and surface hoar, and in many places theĀ  overlying slab may now be primed for human triggering.
Be careful with wind loaded pockets while approaching and climbing ice routes.>Be aware of the potential for large, widely propagating avalanches due to the presence of buried surface hoar.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 4