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Archived

Avalanche Forecast

Jan 11th, 2014–Jan 12th, 2014
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
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
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.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Sunday: Flurries with trace amounts of precipitation, winds from the west at ridgetop 30 to 60 km/h, freezing level at valley bottom.Monday: Flurries with trace amounts of precipitation, strong winds from the W-NW at ridgetop  gusting to 100 km/h, freezing level  rising to 1200 M.Tuesday: No Precipitation in the forecast, moderate to strong winds from the west, freezing levels may rise to 1500m in parts of the forecast area

Avalanche Summary

There have been a few different close calls with large avalanches in the north of this region in the last three weeks. Check out the incident database for more details. Reports from the last 4 days indicate several natural cornice triggered avalanches running to size 3 on east and southeast aspects at treeline and above.

Snowpack Summary

Up to 20 cm of new snow sits on a variety of snow surfaces ranging from stiff wind slab, a soft layer of facetted snow and/or surface hoar. These sit on top of old wind slabs and a couple of persistent weak layers that exist in the upper meter of the relatively thin snowpack. The mid December surface hoar is buried around 30-90 cm. The early December facet/crust combo is buried down 50-150 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last two weeks have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.

Avalanche Problems

Storm Slabs

High winds, warm temperatures and fresh snow have created dangerous avalanche conditions in the backcountry.  Careful consideration is need at this time.  Skiers and sledders may be able to trigger a large  destructive avalanche at this time.
Stick to simple terrain and be aware of what is above you at all times.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Avoid all avalanche terrain.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5

Persistent Slabs

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 5

Deep Persistent Slabs

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 6