Avalanche Forecast

Issued: Mar 19th, 2019 4:46PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Loose Wet and Persistent Slabs.

Avalanche Canada cgarritty, Avalanche Canada

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Another day of strong sun and warm temperatures will maintain very dangerous avalanche conditions on Wednesday. Travel in avalanche terrain is not recommended.

Summary

Confidence

Moderate -

Weather Forecast

Tuesday night: Clear. Light southwest winds. Freezing levels remaining near 3300 metres.Wednesday: Sunny. Light variable winds. Alpine high temperatures around +8 with freezing levels still at 3300 metres, dropping slightly overnight.Thursday: Sunny. Light east winds. Alpine high temperatures around +7 with freezing levels around 3100 metres, remaining elevated overnight.Friday: Sunny. Light variable winds. Alpine high temperatures around +6 with freezing levels around 3000 metres, dropping overnight to 2200 metres by mid-morning Saturday.

Avalanche Summary

Reports from Sunday and Monday showed a continuation of natural loose wet avalanche activity focused on sun exposed aspects, with some releases reaching size 2.5 as they gouged into the snowpack to entrain more mass. Several large persistent slab releases have also been noted failing on large alpine features and reaching size 2.5. Failure planes in these events remain uncertain, but at least one northeast aspect figured in these reports, showing some increasing potential for shaded aspects.Saturday's reports were of significant warming but only small loose wet avalanches. Neighbouring regions (for example Kananaskis Country) where the snowpack is thinner and weaker entered a natural avalanche cycle involving most aspects, most elevations, and most snowpack layers.Looking forward, the type of activity shown above can be expected to continue, expand to all aspects, and perhaps intensify as temperatures remain elevated and overnight cooling remains weak.

Snowpack Summary

Upper snowpack: Getting warm and moist during the day, maybe forming weak crusts overnight that deteriorate during the day. On sunny aspects there may be buried crusts serving as sliding layers. On lee slopes there may be buried hard layers of wind effected snow (buried wind slabs).Mid pack: The mid-snowpack consists of sugary faceted grains (facets) of different hardness. Two older layers of surface hoar still exist down 55-80 and down 95-150 around 1600-1900m. As warmth penetrates into the snowpack each day, it progressively increases strain on these layers.The lower snowpack has recently been reported to be strong in deep snowpack regions, but its strength is in doubt in shallower areas where the long February cold was able to penetrate and weaken even basal snowpack layers. Forecasting how many sunny days and warm nights it's going to take to wake up deeper layers is tough, but we can say with confidence that it's a good time to stand aside and let the mountains shed their coat. Stability will improve greatly when temperatures cool off.

Problems

Loose Wet

An icon showing Loose Wet
Sunshine and warm temperatures will peel away layers or recent snow on sunny slopes as loose wet slides, weaken cornices, and possibly re-energize wind slabs. Expect loose wet avalanche activity to expand to shaded aspects under sustained warming.
Expect shaded aspects to become increasingly prone to loose wet avalanche activity.Be aware of overhead hazards and avoid exposure to avalanche runout zones.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
The weak layers present in our snowpack are undergoing a stress test that increases with each day of warm temperatures and weak overnight cooling. The deeply buried surface hoar layer from mid January is a primary concern at lower elevations.
Remote triggering is a concern, watch out for adjacent slopes.Warming could wake up buried weak layers.Be cautious in shallow snowpack areas where triggering a deeper layer is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Mar 20th, 2019 2:00PM

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