Avalanche Forecast

Archived

Jan 5th, 2023–Jan 6th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Increasing winds will promote wind slab development at tree line and above. These fresh wind slabs sit over a generally weak, faceted snowpack.

Confidence

Moderate

Avalanche Summary

A size 2.5 natural avalanche was observed off the north face of Mt. Kitchener on Thursday, Jan 5. Unable to identify the type of avalanche or failure plane due to visibility.

Snowpack Summary

Widespread surface hoar growth throughout the Jasper region. The top 20-40cm has a varying density with pockets of wind slab developing in exposed terrain at treeline and above. The upper snowpack sits over the Dec 17 persistent weak layer buried 30-40cm deep. The lower snowpack is heavily faceted with depth hoar present at the base of the snowpack. The snowpack ranges from 50-120cm.

Weather Summary

Friday

Mainly cloudy with isolated flurries.

Precipitation: Trace.

Alpine temperature: High -6 °C.

Ridge wind southwest: 15 km/h gusting to 45 km/h.

Freezing level: 1400 metres.

Saturday

Mainly cloudy.

Precipitation: Nil.

Alpine temperature: Low -11 °C, High -6 °C.

Ridge wind southwest: 15-30 km/h.

Freezing level at valley bottom.

Sunday

Mainly cloudy with isolated flurries.

Precipitation: Trace.

Alpine temperature: Low -11 °C, High -7 °C.

Ridge wind southwest: 10 km/h.

Freezing level at valley bottom.

Terrain and Travel Advice

The trees are not a safe haven, travel at treeline requires expert knowledge and diligence.
Make conservative terrain choices and avoid overhead hazard.

Problems

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.

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.