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Avalanche Forecast

Feb 4th, 2017–Feb 5th, 2017
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: South Rockies.

New snow is creating touchy storm slabs: It's time to rein in your terrain choices and stick to simple, low consequence terrain. Avoid all overhead hazard as well - avalanches have the potential to run to valley bottom.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

Significant snowfall through to Monday afternoon.SUNDAY: Periods of snow, accumulation 20-30cm by day's end / Light to moderate southeast wind / Alpine temperature -7MONDAY: Flurries, accumulation 10-20cm / Light to moderate southeast wind / Alpine temperature -20TUESDAY: Scattered flurries / Light southwest wind / Alpine temperature -15

Avalanche Summary

Soft slabs from the storm snow were very reactive to ski cutting and explosives control on Saturday. The size and distribution of avalanches will increase significantly by Sunday afternoon: It's time to seriously dial back the terrain use and stick to simple, low consequence terrain. The possibility of triggering the weak faceted layers deeper in the snowpack remains a concern, and storm slabs may step down to trigger larger, more destructive avalanches.

Snowpack Summary

Taking regional variations into consideration, 15-25cm of new snow typically sits on wind-affected surfaces at higher elevations. This new snow is forming touchy soft slabs on all aspects as winds have been shifting on Saturday. Below 1500 metres you may find an isolated thin breakable rain crust about 1 cm thick. The snowpack is quite variable throughout the region. In deeper areas, the snowpack appears to be well settled with isolated concerns about the mid-December facet layer buried 50-100 cm deep. In shallow snowpack areas and lower elevations, the snowpack is weak and faceted. For instance, in the Elk Valley north area near Crown Mountain last week the height of snow was 90 cm with foot penetration of 80 cm; or almost to ground. In these areas, the wind has formed isolated hard slabs above weak facets and created the potential for large persistent slab avalanches.

Avalanche Problems

Storm Slabs

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Deep Persistent Slabs

Triggering deeper weak layers remains possible where hard slabs sit above weak sugary snow. This is most likely in thin snowpack parts of the region.
Danger exists where denser snow overlies weak, sugary snow below.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3