Avalanche Forecast

Issued: Apr 15th, 2023 4:00PM

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

Avalanche Canada GL, Avalanche Canada

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Incoming snow or rain, wind and warmer temperatures on Sunday. Watch for changing conditions and how they effect the avalanche hazard.

Summary

Confidence

High

Avalanche Summary

Natural activity has tapered off but still requires vigilance and careful assessments. Explosive control on previously controlled Parker Slabs on Friday produced no results.

A size 2 skier accidental triggered deep persistent slab avalanche was reported on the regular approach to the north glacier on Mt. Athabasca on Thursday.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

Up to 20cm of snow sits on multiple crusts up to 2400m. Snow pit tests are showing results in the weak facet crystals below these crusts on south aspects. Above 2400m the surface snow is dry. The snowpack below 1800m is in a daily melt-freeze cycle. The mid-pack above this elevation consists of multiple layers of sun crusts or facets. Depth hoar and basal facets make up the base of the snowpack.

Weather Summary

Expect flurries with up to 6cm of precip and an alpine high of 0 °C. Moderate southwest winds with gusts up to 40km/h. Freezing level is expected to rise to 2300m during the day.

Monday will see a mix of sun and cloud with isolated flurries. Alpine temperatures will range from a low of -10 °C and a high of -5 °C. Ridge winds will be 15 km/h from the southwest gusting to 40 km/h. Freezing level should remain at valley bottom.

Terrain and Travel Advice

  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Remember that in the spring strong solar radiation and warm temperatures can weaken the snow in a matter of minutes.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The bottom of the snowpack is inherently weak with well-developed Facets and Depth Hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Loose Wet

An icon showing Loose Wet

Stronger overnight freezes may keep this problem in check until mid to late afternoons. Watch out if the sun comes out. Wet loose avalanches can step-down to our basal facets in steep terrain resulting in large avalanches.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 1.5

Persistent Slabs

An icon showing Persistent Slabs

A cornucopia of persistent weak layers in the midpack can be found as facets on polar aspects and sun crusts on solar aspects.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Apr 16th, 2023 4:00PM

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