Avalanche Forecast

Archived

Nov 25th, 2024–Nov 29th, 2024

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

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

Recent snow has improved ski conditions at the Icefields. Lingering wind slabs exist and there is significant uncertainty around the October crust, which lurks at the base of the snowpack.

It’s a good time to let the snowpack form and take a conservative approach to early-season fun.

Confidence

Moderate

Avalanche Summary

Several size 1 loose dry avalanches out of steep rocky terrain were reported Saturday as the sun poked out. One of these pulled a sz. 1.5 windslab.

On Sunday, ski hills south of Jasper National Park reported two size 2 natural avalanches and two size two explosive triggered avalanches. All of these avalanches ran on the October crust at the bottom of the snowpack.

Snowpack Summary

10-20 cms of recent storm snow sits on old windslabs and a faceted midpack. There is a thin crust 20-30cm below the surface, as well as a notable 5-15 cm thick crust from October near the base of the snowpack, surrounded by facets above and below. There is a lot of uncertainty about what it will take to trigger this layer.

Snow depth at Treeline is approximately 70 cm tapering off rapidly below. In the Alpine there is around 80 cm with variability due to wind redistributing the snow.

Weather Summary

Tuesday

Cloudy with sunny periods. Low -15 °C and a High -11 °C with winds from the west 10 km/h.

Wednesday

A mix of sun and cloud with isolated flurries. Trace precipitation. Low -16 °C, High -11 °C with winds from the west: 10-25 km/h.

Thursday

Cloudy with sunny periods and isolated flurries. Trace precipitation. Alpine temperature: Low -17 °C, High -12 °C with winds from the southwest: 10 km/h.

Terrain and Travel Advice

Be careful as you transition into wind-affected terrain.
Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.

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.