Avalanche Forecast

Archived

Feb 6th, 2023–Feb 7th, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Incoming storm expected to produce up to 30cm new snow beginning late Monday through Tuesday. Forecast winds and significant precipitation will be the first major test to our weak snowpack. Highway 93N closure planned for 1700hrs on Monday Parker Summer to Saskatchewan Crossing. Check 511 for updates.

Confidence

Moderate

Avalanche Summary

Feb 5th Icefield patrol reported one large natural avalanche triggered by glacial ice. No more avalanches observed, however the visibility was very poor.

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

Snowpack Summary

Moderate to strong southwest wind continues to strip snow in exposed alpine features creating wind slab in the alpine and into exposed tree line. A weak melt freeze crust facet combo down 25cm below 2100m is showing sudden collapse results in snow pit tests. Generally, the bottom of the snowpack is weak facets and depth hoar. The snowpack ranges from 50 to 120cm.

Weather Summary

Snowfall will increase in intensity Monday night through Tuesday with up to 30cm possible by the end of Tuesday in the Icefields area. Winds will be moderate to strong from the southwest - freezing level will remain at valley bottom. Clearing trend on Wednesday.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Watch for signs of slab formation throughout the day.

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.

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.

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.