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Avalanche Forecast

Archived

Nov 21st, 2015–Nov 22nd, 2015

Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.
Alpine
Below Threshold.
Treeline
Below Threshold.
Below Treeline
Below Threshold.

Regions

Purcells.

Given the very limited information on hand for this bulletin, I would tread cautiously this weekend and take the time to gather snowpack information as I go. As always, we would love for you to submit any observations from your day to the MIN.

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

High pressure will persist over the region through Sunday before an advancing cold from the North brings light snowfall Monday and Tuesday. Sunday: Mainly clear, a temperature inversion may exist in the morning but freezing levels are forecast to fall back to the valley floor throughout the day. Monday: 2 to10 cm of snow, southwesterly wind, a high of -10C in the alpine. Tuesday: 5 to 10 cm of snow, northerly wind, a high of -15C in the alpine.

Avalanche Summary

Im working with limited observations but there havent been any recent reports of avalanche activity. However, the avalanche cycle that occurred during and immediately after the storm earlier in the week produced some large avalanches. Last weekend there was a report submitted to the Mountain Information Network of rider a triggered avalanche that released on basal facets at treeline in the Dogtooth range near Golden.

Snowpack Summary

Up to 50cm of low density snow fell in the storm earlier this week. A MIN report from the south of the region suggest that some of this fell as rain forming a crust up to 1900m near Kimberley. Moderate westerly winds are likely to have formed pockets of windslab on east and northeast aspects. Below this we're dealing with a complex snowpack. A couple of layers of surface hoar were formed earlier in the month. Where they exist, they are likely to be found buried down 50 to 100 cm. Depending on where you dig, you might also find a couple of crusts. It would be wise to test these layers before committing to a slope. Facets are likely to be found just above the ground at higher elevations in the alpine. Remember that it's still a thin snowpack. Rocks and stumps may be lurking unseen just below the surface. Ride with care!

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.