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Avalanche Forecast

Mar 20th, 2017–Mar 21st, 2017
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
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
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: Jasper.

Avalanche control work on Monday produced numerous class 3 avalanches from alpine terrain. Stick to low angle supported terrain until the snow pack settles down.

Weather Forecast

Unsettled warmer weather for the next few days. Overnight -10.  Tomorrow mainly cloudy with isolated flurries. Freezing level 2100m. Alpine highs 0 C. Ridge winds south 10-20 km/h. More sun to the north near the townsite. On Wednesday 5-10cm of new snow lesser amount near the townsite with more sunshine.

Snowpack Summary

The 50cm of snow that fell last week and into the weekend has formed wind slabs up to 1.5m's thick at and above treeline. Large cornices loom above. Below the slab is a mid-pack with several crusts and persistent instabilities of facets and surface hoar. Closer to the ground a weak base around the November rain crust and depth hoar below.

Avalanche Summary

A widespread avalanche cycle took place over the weekend with crowns up to a kilometer long and in places 2m deep. The largest  are size 3.5 and have run full path several stepped to basal layers near ground. From treeline less activity and more in the class 2-2.5 range. Control work today produced numerous size 3 avalanches from the alpine.

Confidence

Freezing levels are uncertain on Wednesday

Avalanche Problems

Wind Slabs

60cm of storm snow over the week has formed a dangerous windslab. Wide crowns up to 2m and a km long have been seen across the range. In shallow areas several of these stepped to ground. All are running a long way into the valley.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 3

Cornices

Large cornices on lee features some visibility detaching. Those that have released are triggering large avalanches from alpine terrain
Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Deep Persistent Slabs

The widespread observations of large and deep avalanches indicates strongly that many of the weekends avalanches went on this layer particularly where the snowpack is shallow and in rocky start zones.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be careful with low angle slopes that may not normally be a concern.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 4