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Archived

Avalanche Forecast

Jan 21st, 2020–Jan 22nd, 2020
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
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: Kootenay Boundary.

Recent southerly winds have promoted wind slab development at upper elevations. 

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT - Flurries, 5 cm / southwest wind, 20-30 km/h / alpine high temperature near -5

WEDNESDAY - Cloudy with isolated flurries / southwest wind, 20-30 km/h / alpine high temperature near -4

THURSDAY - Flurries, 5-10 cm / southwest wind, 30-40 km/h / alpine high temperature near 0 / freezing level 1500 m

FRIDAY - Flurries, 5-15 cm / south wind, 20-40 km/h / alpine high temperature near 0 / freezing level 1500 m

Avalanche Summary

Reports on Monday indicate a few explosives controlled storm slab avalanches size 1.5 to 2 on north and east aspects between 2000 and 2200 m. These were reported as 15-30 cm deep.

On Sunday there was a report of an explosives triggered size 2.5 loose snow avalanche.

No new persistent slab avalanches were observed in the past few days, but this region has been highlighted for recent persistent slab avalanche activity. A number of natural and explosives triggered persistent slab avalanches up to size 3 were reported just over a week ago.

Snowpack Summary

35 to 65 cm of new snow from last weekend has been redistributed by moderate to strong winds from a variety of directions. This combined with relatively warm temperatures, will have likely formed fresh slabs in many areas.

There are two weak layers of surface hoar found around 70 to 130 cm below the snow surface. These layers are especially concerning in steep, sheltered, and shallow rocky areas.

The base of the snowpack in many parts of the region consists of weak sugary faceted crystals around a melt-freeze crust.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Avalanche Problems

Wind Slabs

Recent new snow and wind has likely formed pockets of wind slab in lee terrain features.

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

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

Several persistent weak layers are buried in the snowpack. It is possible for humans to trigger them, or for smaller avalanches to step down, resulting in very large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1.5 - 3