Purcells

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Fair - Wind effect is extremely variable

Synopsis: An off shore Rex Block keeps the province under cold, dry northerly flow for the forecast period. But the models are starting to agree on a solution that shows the blocking pattern breaking down giving way to a steady flow of Pacific Storms early next week. Time will tell if this is all conjecture and hope, or something a bit more substantive.Thursday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, E Friday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, SWSaturday: Sky: Clear; Freezing Level: Valley Bottom; Precip: Nil Wind: Light, NE

Wind slabs sensitive to both natural and human triggering continue to be reported. The interesting thing is that they seam to be growing in size. On Tuesday we received a report of a size 2 wind slab popping out of a steep west facing moraine feature.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.

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.