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Archived

Avalanche Forecast

Apr 23rd, 2023–Apr 24th, 2023
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Jasper, Maligne, Marmot, Miette Lake, Pyramid.

Sunday night is expected to have less of an overnight freeze than previous nights and Monday may start warm. The thick high clouds potentially will hold onto the warm air overnight. If Monday starts warm, this could increase the reactivity of cornices and deep persistent slabs.

Confidence

Moderate

Avalanche Summary

There was an avalanche Fatality in Banff Park near Lake Louise Saturday from a deep large human triggered slide. On Friday, 2 natural large deep avalanches were observed, both on East aspect in the alpine triggered by a cornice failure.

Maligne road patrol saw no new natural avalanche activity on Friday.

Post avalanche observations to the MIN.

Snowpack Summary

10cm of new snow from last week has settled onto sun crusts on solar aspects with a melt-freeze crust below tree line. Old wind slab is on exposed alpine terrain.

A weak layer of sun crust or facets lingers in the mid-pack but the main concern is the depth hoar and basal facets at the bottom of the snowpack causing our deep persistent slab problem.

Weather Summary

Parkers ridge weather on Monday will bring sun and cloud, no new snow, high of 1 °C, light winds, and 2400m freezing level. Tuesday will have sun with flurries, -5 °C in the morning then a high of -2 °C, gusting 35 km/h winds, and 1900m freezing level. Wednesday will be sun and cloud, -7 to 0 °C, light winds, and 2200m freezing level.

Terrain and Travel Advice

  • Cornices become weak with daytime heating.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Avoid exposure to slopes that have cornices overhead.

Avalanche Problems

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 - 4

Cornices

With increasing daytime temperatures and sun effect, mature cornices have a potential to trigger the lingering deep persistent slab below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 3

Loose Wet

There is expected to be less of a freeze Sunday night and Monday the freezing level will be 2300m or higher depending on weather variables.

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

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2