Avalanche Forecast

Issued: Mar 19th, 2021 4:00PM

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

Avalanche Canada cgarritty, Avalanche Canada

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Steady light snowfall and elevated winds are keeping winter alive up high. Be ready to manage a typical array of wind slab and cornice hazards as you gain elevation.

Summary

Confidence

High -

Weather Forecast

Friday night: Cloudy with continuing scattered flurries and a trace to 5 cm of new snow. Moderate to strong southwest winds.

Saturday: Mainly cloudy with isolated flurries and a trace of new snow, increasing a bit overnight. Moderate to strong northwest winds shifting southwest and increasing overnight. Alpine high temperatures around -13.

Sunday: Cloudy with continuing scattered flurries with another trace to 5 cm of new snow (up to 10 cm with overnight accumulations). Strong to extreme south winds easing to light southwest in the afternoon. Alpine high temperatures around -7.

Monday: Cloudy with isolated flurries. Light southwest winds. Alpine high temperatures around -8.

Avalanche Summary

No new natural avalanches were reported over the past few days. That said, a guide on belay was able to trigger a large (size 2), touchy cornice chunk with a kick on Wednesday afternoon at 1650 metres in the Hudson Bay Mountain area. A few size 1 skier triggered wind slab avalanches in the alpine were reported on Monday.

Snowpack Summary

5-10 cm of new low density snow was added to the surface over Thursday night and Friday with elevated southwest wind during the same period. A similar pattern is expected from Saturday through to Sunday. Fresh wind slab and cornice hazards likely exist (and will continue to form) on leeward features near ridgetops. 

In more sheltered areas, the new snow otherwise adds to 20-30 cm of storm snow from last weekend. In the southwest of the region these totals are closer to 50-100 cm. At lower elevations, much of the weekend's precipitation fell as rain, creating crusty surfaces now buried by low density snow.

Collectively, our new and recent snow overlies a variety of surfaces, including hard wind affected snow at alpine elevations, weak surface hoar crystals on northerly aspects and in sheltered terrain features around treeline, or a melt-freeze crust on southerly aspects and below treeline.

The mid and lower snowpack is reported as well settled and strong in most areas. However, weak facets exist at the base of the snowpack in the more shallow snowpack zones within much of the region and always have the potential of being triggered on steep, rocky slopes with a shallow or thin to thick snowpack; especially with large loads such as a cornice fall.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Wind Slabs

An icon showing Wind Slabs

Light new snow and shifting winds will likely continue to form wind slabs that may be reactive to human triggers on lee and cross-loaded terrain in the alpine. Keep your guard up on steep, sheltered, north-facing slopes where recent accumulations may overlie a weak layer of surface hoar.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 20th, 2021 4:00PM

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