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Archived

Avalanche Forecast

Feb 4th, 2014–Feb 5th, 2014
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
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
1: Low
The avalanche danger rating in the alpine will be low
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

Regions: Purcells.

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Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Synopsis:  A very strong ridge of high pressure continues to dominate the weather pattern.  In the extended period the models are not breaking down the ridge as quickly, so it looks like Saturday will be dry throughout the province.Wednesday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, NE | Mod, NE at ridgetop.Thursday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, NE Friday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, NE

Avalanche Summary

Explosive control work on a steep north facing slope in the alpine produced an anomalous size 2.5 avalanche in the central portion of the region Saturday. On Sunday/Monday activity was limited to skier provoked sluffing.

Snowpack Summary

The January 29th system left 10 - 20 cm of snowfall in it's wake with the greatest accumulations in the southern portion of the region.  North winds redistributed the snow resulting in reverse loading of lee features in the alpine with reactive pockets of wind slab up to 40cm deep.The new snow and wind slabs rest on a significant weakness composed of of large surface hoar (widespread in most sheltered and shaded areas at all elevations), a sun crust on south facing slopes, faceted grains (in colder areas or areas with a thinner snowpack), or a combination of the above. This variable weak layer is expected to become a problem when/if it finally starts snowing again. The rest of the upper and mid-snowpack are generally well consolidated.In isolated areas where the snowpack is thinner or in steep rocky features a facet/crust weakness near the ground remains a concern. In most places the depth of this layer combined with the strength of the overlying slab makes triggering an avalanche unlikely. However, if you were unlucky enough to find a weak spot the consequences could be deadly serious.

Avalanche Problems

Wind Slabs

Erratic winds are forming thin slabs in the alpine that rest on a variety of persistent weaknesses. This combination will keep both the active sluffing and small wind slab problem on the front page longer than we're normally accustomed to.
Watch for terrain traps where small amounts of snow will acumulate into deep deposits.>On steep slopes, pull over periodically or cut into a new line to manage sluffing.>Carefully consider the impact a thin wind slab will have on your proposed line, especially in high consequence terrain. Have a backup line in mind in case you need to seek more sheltered riding. >Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3