Avalanche Forecast

Issued: Mar 17th, 2019 3:52PM

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 istorm, Avalanche Canada

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Sunshine and warmth may feel good to us, but it doesn't help the snow. It's a good time to step aside, watch from afar, and let the mountains shed some snow. Riding will be better, or at least safer, when it cools off in a few days.

Summary

Confidence

Moderate -

Weather Forecast

A significant warm-up is happening and will continue through the week with above freezing level to the summits. Unfortunately, very little overnight re-freeze is expected during the warm spell.SUNDAY NIGHT: Clouds disappearing, warming temperatures overnight with above freezing temperatures at treeline in the morning.MONDAY: Clear and dry. Freezing level around 3000 m with no overnight freeze. Light south wind.TUESDAY: similar to Monday.WEDNESDAY: similar to Monday and Tuesday but possibly slightly lower freezing level, say 2500 m.

Avalanche Summary

Fewer avalanche activity reports on Saturday and Sunday with smallish loose wet, loose dry, and windslabs.For me the most important avalanche data over the past few days were SEVERAL REMOTELY TRIGGERED AVALANCHES (some of these reports were from areas outside the forecast region but are relevant to the region's conditions). Skiers are whumpfing the snowpack, often when they group up, with avalanches releasing at a distance (sometimes on the slope above). Reports include this happening on previously skied terrain, include releasing several avalanches from a single whumpf, and avalanches releasing and running over normal "ski lines".

Snowpack Summary

Between 50 and 100 cm of "settled" snow since the drought ended March 10. At lower elevations the most recent precipitation came as rain. The recent snow is settling into a slab with the warm temperatures: however, it's covering a wide variety of old snow surfaces: crusts on solar aspects, facets up high, and surface hoar in sheltered locations. Not much further below this storm snow interface is a second weak layer buried on February 19 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 highlights remotely triggered avalanches: the recent storm snow is settling into a cohesive slab, the old cold weak layers remain. For slightly complex reasons (snowpack creep, strain rates, viscous coupling, and similar geeky snow science stuff) warm temperatures are keeping the snow stability balance near a tipping point.

Problems

Loose Wet

An icon showing Loose Wet
Sunshine and warming will weaken the snowpack. At first this will affect "solar" or sunny aspects but over the next few days weakening is likely to include all aspects and elevations.
Parking, eating lunch, and regrouping in runout zones is bad practice.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Continue to make conservative terrain choices and avoid overhead avalanche hazard.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
Previous weaknesses in the upper snowpack (sugary facets) remain active. A weak layer buried around 60 cm below the surface is still sensitive to triggering too. There are numerous reports of remotely triggered avalanches.
Remote triggering is a concern, watch out for adjacent slopes.Storm or wind slabs may step down to deeper layers resulting in large avalanches.Avalanche hazard is expected to increase throughout the day, think carefully about your egress.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Valid until: Mar 18th, 2019 2:00PM