Avalanche Forecast

Archived

Apr 26th, 2023–Apr 27th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Regions

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

We will get one more weak overnight freeze on Thursday night before the freezing levels skyrocket Friday afternoon. Watch out for pockets of wind slab as convective flurries can drop vastly different amounts of snow from valley to valley.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported and no road patrol on the Icefields Parkway today.

Post avalanche observations to the MIN.

Snowpack Summary

Sun crusts on solar aspects into the alpine and a melt-freeze crust at tree line and below on all aspects. Small wind slabs in the alpine from moderate to strong SW winds with 2-5cm of recent snow available for transport. A layer of sun crust or facets lingers in the mid-pack. The main concern is the depth hoar and basal facets at the bottom causing our deep persistent slab problem.

Weather Summary

Thursday

Sunny with cloudy periods

Alpine temperature: High 1 C

Ridge wind west: 10-25 km/h

Freezing level 2400m

Friday

Sunny with cloudy periods

Alpine temperature: Low -1 C

Ridge wind west: 10-20 km/h

Freezing level 3200 m

Saturday

Mix of sun and cloud

Alpine temperature: Low 4 C

Ridge wind southwest: 10 km/h

Freezing level 3500 m

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.