Avalanche Forecast

Issued: Mar 18th, 2019 4:12PM

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

Avalanche Canada cgarritty, Avalanche Canada

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This is a good time to avoid avalanche terrain.

Summary

Confidence

High -

Weather Forecast

Monday night: Clear. Light to moderate south winds with freezing levels remaining near 3000 metres.Tuesday: Sunny. Light to moderate south winds. Alpine high temperatures around +8 with freezing levels remaining near 3000 metres and staying elevated overnight.Wednesday: A mix of sun and cloud. Light east or southeast winds. Alpine high temperatures around +5 with freezing levels around 2700 metres and decreasing a bit overnight.Thursday: A mix of sun and cloud with cloud increasing over the day. Light to moderate south winds. Alpine temperatures declining from +4 to +1 over the day as freezing levels drop from 2500 to 2000 metres, steadying overnight.

Avalanche Summary

Reports from the Shames area on Sunday showed evidence of what was likely a widespread natural avalanche cycle that produced at least several very large (size 3) slab avalanches running the full extent of their respective avalanche paths. More numerous audible large avalanches were also reported. The failure plane in these slides appeared to have been our most recent storm snow interface. Even more numerous, smaller loose wet avalanches were observed. All of this activity was focused on steep, sun-exposed aspects. This type of activity can be expected to continue, potentially expand to all aspects, and intensify as temperatures remain elevated and overnight cooling remains weak.

Snowpack Summary

Between 50 and 100 cm of settled snow forms the upper snowpack, the product of storms since the drought ended on March 10. At lower elevations this precipitation came as rain. With the help of warming temperatures, the recent snow has settled into a slab that covers a variety of old snow surfaces. These include crusts on solar aspects, facets on shaded aspects at higher elevations, and surface hoar in shaded and sheltered locations. Not much further below this storm snow interface is a second weak layer buried on February 19, primarily made up of weak facets and surface hoar crystals. Recent avalanche activity was more or less equally split between these two layers. The lower snowpack is generally strong.The Avalanche Activity section below shows heightened recent avalanche activity. Our recent storm snow has settled into an unstable slab over a range of lingering old weak layers formed during the cold spell. For the near term, expect warm temperatures to keep the snow stability balance near or beyond its tipping point.

Problems

Loose Wet

An icon showing Loose Wet
Sunshine and warming will destabilize surface snow - especially on steep, sunny slopes. This problem is likely to expand to include shaded aspects under sustained warming. Large loose wet avalanches may impact lower elevations.
Be aware of sustained warming causing loose wet avalanche problems to include shaded aspects.Avoid exposure to steep, sun exposed slopes while solar radiation is strong.Be aware of overhead hazards and avoid lingering in runout zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Previous weaknesses in the upper snowpack remain active. A weak layer buried around 60 cm below the surface is still sensitive to triggering. Heightened avalanche activity in the upper snowpack is expected to continue as warm temperatures persist.
Avalanche hazard is expected to increase throughout the day, think carefully about your egress.Storm or wind slabs may step down to deeper layers resulting in large avalanches.Remote triggering is a concern, watch out for adjacent slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3

Valid until: Mar 19th, 2019 2:00PM

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