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Avalanche Forecast

Jan 7th, 2013–Jan 8th, 2013
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
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
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: Sea To Sky.

A significant storm is expected to impact this region starting Tuesday afternoon and overnight into Wednesday. Expect very dangerous avalanche conditions in this region through this period.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Tuesday: A significant storm is expected to hit the region starting Tuesday around noon and ramping up during the afternoon and overnight. Expect around 15 cm new snow expected by the end of the day and another 15-20 overnight. Ridgetop winds gusting to 75 km/h from the southwest. Freezing level rising briefly to around 1500m late on Tuesday, but mostly staying around 800 m.Wednesday: Snowfall lingering until noon, then clearing. Temperatures falling rapidly. Winds diminishing.Thursday: Dry and cold. Temperatures around -8C. Winds becoming light northerly.

Avalanche Summary

Relatively small soft slab avalanches were easily triggered on Monday. With further loading by new snow, the potential for larger, more destructive avalanches will increase through Tuesday and Wednesday.

Snowpack Summary

The new snow is bonding poorly to existing snow surfaces that include surface hoar (up to 20 mm in size), facets, hard wind slabs or a sun crust. The upper storm slab has so far been reported as thin (20-30 cm) and soft. However, with more snow it will rapidly increase in thickness and danger. Recent SE winds have formed new wind slabs at alpine and treeline elevations. No significant shears have been observed recently below the recent storm snow in the mid snowpack layers. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in steep, shallow, rocky terrain where more facetting has taken place.

Avalanche Problems

Storm Slabs

The new snow has set up touchy slab conditions in many areas, especially where strong southeastely winds have created thicker and denser deposits.
Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Avoid freshly wind loaded features.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5