Avalanche Forecast

Archived

Apr 15th, 2023–Apr 16th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

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

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

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.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.