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Avalanche Forecast

Mar 9th, 2016–Mar 10th, 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
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
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: Purcells.

A storm on Thursday will bring high avalanche danger to the Purcell Mountains.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Thursday: 10-20 cm new snow expected with the heaviest amounts likely to be in the south of the region. Strong southwest winds up to 80 km/h expected at ridgetop. Freezing levels expected to rise to 1900 m near noon.  Friday: Dry with some clear spells. Winds becoming light southeasterly. Freezing level around 1700 m. Saturday: 5-10 cm new snow, with moderate southwesterly winds and freezing level around 1800 m.

Avalanche Summary

On Tuesday, several large (size 3) avalanches were reported from south-facing slopes near Golden. On Monday, natural avalanches up to size 3.0 and human-triggered avalanches up to size 1.5 were reported from northerly aspects, mostly in the alpine.

Snowpack Summary

30-70 cm recent storm snow overlies a prominent weak layer buried on or around Feb-27. The deepest snow amounts appear the be in the west central area near Kootenay Lake. The Feb-27 weak layer comprises surface hoar and a crust. It has been widely reported but recent snowpack test results are mixed, with some tests indicating this layer is gaining strength, while others indicating it can still fail with sudden "pop" results. A deeper weak layer from mid-February is now down 50-80cm. The early January surface hoar/facet layer is typically down 70-120cm. Triggering an avalanche on either of these layers has become unlikely but either still has the isolated potential to produce very large avalanches with a heavy trigger.

Avalanche Problems

Storm Slabs

Storm and wind-slab avalanches are expected to run in response to new snow and wind, particularly on north through east aspects.
Minimize exposure during periods of heavy loading from new snow, wind.>

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

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 4

Persistent Slabs

A crust/surface hoar layer buried approximately 60 cm below the surface is triggerable by people on sleds or on skis. This layer could also avalanche naturally during stormy weather and produce large avalanches.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 3 - 5