Avalanche Forecast

Issued: Jan 21st, 2014 8:52AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs.

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

A weak disturbance is expected to bring flurries on Wednesday morning before the ridge rebuilds once again.Wednesday: Flurries, with minimal accumulation. Winds 10-20 km/h from the NW. Alpine temperatures are expected to fall (max of -3C expected) and the inversion temporarily disappears.Thursday: Dry. Alpine temperatures should stay cool, around -4C, but rising late in the afternoon. Ridgetop winds around 10-20 km/h from the NW.Friday: Dry. The inversion returns with an above freezing layer from around 2200 to 3200m. Winds around 20 km/h from the NW.

Avalanche Summary

On Tuesday, explosive avalanche control produced avalanches up to size 2 that ran on the basal facets on N and NW aspects in the alpine. No natural activity has been reported for several days.

Snowpack Summary

Between 60cm and 90cm of well settled storm snow exists as a stubborn hard wind slab in many exposed areas. Thanks to recent warming, steep, sun exposed slopes have seen a daily melt-freeze cycle while surface hoar has been growing in some shaded terrain. Below the recently formed storm slab you may find surface hoar buried around January 8th, although no recent avalanche reports have been attributed to this layer. In the mid to lower pack you may find a surface hoar layer buried in mid December. Further down you may also find the December facet/crust combo. These layers are likely gaining strength, but professional operators are treating them with caution.The biggest concern throughout the region is a layer of weak sugary depth hoar at the base of the snowpack which may coexist with a crust which formed in October. I would continue to be suspicious of any large or unsupported upper elevation slopes, especially if they haven't already avalanched. Possible triggers include a heavy load over a thin spot, a cornice fall or rapid temperature change. Any avalanche failing at this interface would be highly destructive.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The chance of triggering a deep persistent slab is greatly reduced. However if you did trigger such an avalanche, the consequences would be great. The most suspect slopes would be thin or variable alpine start zones on steep convex slopes.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Caution around convexities or areas with a thin or variable snowpack.>Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Jan 22nd, 2014 2:00PM

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