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Avalanche Forecast

Feb 15th, 2015–Feb 16th, 2015
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Purcells.

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Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Monday, Tuesday and Wednesday are expected to be dry and cool, with sunny periods. Winds are generally light from the NW. The freezing level is at valley floor by night and rising to around 1200 m by day. The next storm system may arrive late on Wednesday, but weather models are not in agreement about this.

Avalanche Summary

Several size 1.5-3 avalanches were triggered naturally and with explosives over the last few days in response to storm loading, wind and warm temperatures. A number of cornice collapses and an ice fall have also been reported. Last Wednesday, a skier took a ride in a size 2 persistent slab which failed on the mid-Jan layer in the Dogtooth range. Now that temperatures have cooled, avalanche activity is likely to ease, although direct sun may spark a new avalanche cycle on steep slopes or cause cornices to fail.

Snowpack Summary

Now that the weather has finally cooled after ten days of very warm temperatures and bursts of rain, surface crusts have formed to at least 2000 m. Underneath newly formed crusts, you may find moist snow for a few days yet. At alpine elevations, new wind slabs or storm slabs may be found. Cornices are large and weak. The late-Jan crust/surface hoar layer is 1-2 m deep in the west, and can be found within the upper metre of the snowpack further east. It is variably reactive and still the main concern in many areas. The mid-January surface hoar, deeper again, remains problematic in some areas. The mid-December weak layer may still be on the radar in isolated areas in the east. The mid-November weak layer of crusts and facets can still be found near the bottom of the snowpack. It seems to have been reawakened with warming and has been triggered by explosives during the recent warm spell, taking the entire snowpack with it.

Avalanche Problems

Persistent Slabs

Persistent slabs are most likely to be triggered from thin snowpack areas, or with large triggers like cornice fall or an avalanche stepping down.
Avoid common trigger points like convexities or areas with a thin or variable snowpack.>Do not travel on slopes that are exposed to cornices overhead.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6

Wind Slabs

Wind slabs may be lurking on lee and cross-loaded features in the alpine. Cornices are weak and may collapse.
Give cornices a wide berth when travelling on or below ridges.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3