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Archived

Avalanche Forecast

Jan 28th, 2018–Jan 29th, 2018
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
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
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Glacier.

The snowpack is complex, with multiple weak layers stacking up. Conservative terrain choices are essential as a large winter storm approaches and natural avalanche occurrences will increase.Human triggering of avalanches remains likely.

Weather Forecast

Cloud with snow starting late this morning, up to 8cm of accumulation today and 10cm tonight. Alpine high of -6, winds from the south 20km/hr. Freezing levels expected to rise up to 1600m Monday as the atmospheric river pushes inland with 60cm of snow by Tuesday morning.

Snowpack Summary

10cm in past 24hrs, 60cm of settling storm snow with 160cm of snow accumulation over the past two weeks. Expect to find pockets of wind slab along ridge lines and lee features due to the moderate south winds in the Alpine. The Jan 16 surface hoar is down ~60cm, Jan 4 down ~80cm and Dec 15 down ~1m+ making for a complex sandwich of weak layers.

Avalanche Summary

Snowboarder triggered size 2 yesterday, see Avalanche Canada Mountain Information Network (MIN) for more details.Test results showing the Jan 16 surface hoar (5-10mm) down ~60cm, fails suddenly and has a high propagation potential, which could result in large avalanches.No new natural avalanches observed along the highway corridor yesterday.

Confidence

Intensity of incoming weather systems is uncertain on Sunday

Avalanche Problems

Wind Slabs

Moderate southerly winds have redistributed storm snow into pockets of wind slab. The slab will be most sensitive in lee areas at ridge line and exposed areas at tree line. If triggered, the slab could step down to deeper weak layers.
If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

Persistent weak layers present a lower likelihood / high consequence scenario with the Jan 16th, 4th and Dec 15th surface hoar layers. These layers could be sensitive to human triggering in thin areas, or overloads from wind slab avalanches.
Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1.5 - 3