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Archived

Avalanche Forecast

Nov 27th, 2017–Nov 28th, 2017
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

This forecast is based on limited information. There is much uncertainty, particularly how weak layers may respond to human triggers. Treat this as a first estimation of avalanche danger and adjust your terrain choices based on observed conditions.

Confidence

Low - Due to the number of field observations

Weather Forecast

Tuesday: Around 5 cm new snow expected with freezing levels around 900 m. Winds strong southerly in the morning, becoming westerly later on.Wednesday: Flurries or light snow. Freezing levels around 900 m. Winds strong southwesterly.Thursday: Flurries or light snow. Freezing levelst around 500 m. Winds strong westerly.

Avalanche Summary

Small slab avalanches and loose dry avalanches were reported from the west of the region over the weekend. Previously, (last Wednesday), several estimated Size 2.5-3 avalanches wereobserved on the Kathlyn face of  Hudson Bay Mountain. Please post your observations to the Mountain Information Network. (MIN)

Snowpack Summary

Snowpack depths over the south of the region are above average for late November, with total depths of approximately 150 cm present at treeline elevations and above. The past week of stormy weather delivered about 60 cm of new snow to form the upper snowpack in the region. A thin rain crust may exist at mid-depth within this new snow. Below the new snow, about 20-30 cm of settled storm snow lies above the widespread late October crust. This October crust is present near the base of the snowpack at all elevations and features a layer of weak, sugary grains above it. This "crust/facet combo" layer remains an ongoing concern for step-down potential from large triggers such as a storm slab release. This layer is less of a concern below treeline where it is broken up by vegetation near the ground.

Avalanche Problems

Wind Slabs

New snow and wind inputs continue to promote storm slab formation. Expect slab formation to be more pronounced at higher elevations that see more wind effect.
Watch for signs of instability such as whumpfing or cracking.Avoid steep convexities and areas with variable snow distribution.

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The late October crust lies near the base of the snowpack and a layer of weak, sugary snow sits above it. This layer may react to a heavy trigger like a storm slab release. The first evidence of avalanche activity on this layer was recently reported.
If triggered, storm slabs may step down to deeper layers and result in large avalanches.Be aware of the potential for large avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3