Avalanche Forecast

Archived

Apr 18th, 2023–Apr 19th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Regions

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

The weather is proving difficult to forecast across the region. Localized storm slabs and building windslabs are possible. It's a good time to take a step back and give the snowpack time to stabilize.

Confidence

Moderate

Avalanche Summary

No new reports of natural avalanche activity but still be vigilant and make careful assessments.

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

Snowpack Summary

New snow continues to build around the Icefields area and sits on top of a variety of surfaces - crusts on solar aspects & BTL and old wind pressed/ slab on exposed northerly aspects.

BTL is in a daily melt-freeze cycle. At TL, the mid-pack consists of multiple layers of sun crusts or facets and shows long propagation potential on connected features. Depth hoar and basal facets at the base.

Weather Summary

Weather models are a bit wacky right now. It's the result of forecasted convective storms.

Snowfall overnight Tuesday is expected to be most intense around the Icefields (~10-15cm), Parkers Ridge, and along the divide. Flurries will continue through Wednesday and overnight.

Look for detailed weather products and tutorials at Avalanche Canada

Terrain and Travel Advice

If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.

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.