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Avalanche Forecast

Archived

Nov 20th, 2023–Nov 21st, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Early Season
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Early Season
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Early Season

Regions

Glacier.

A sudden rise in Alpine temps, coupled with sunshine and strong winds, may spike the avalanche danger, especially on sunny slopes.

Early season hazards exist everywhere.

The Winter Permit System started on Nov 16! Take the quiz, get your annual permit, and know what areas are open before you venture into the backcountry.

Confidence

Low

Avalanche Summary

Several small natural avalanches were observed in the hwy corridor off Tupper and MacDonald, ranging from sz 1-2, all from steep to extreme terrain. A field team observed a sz 2, failing on the ground, near Christiana Ridge from a very steep SE aspect, likely from Sunday.

Snowpack Summary

The height of snow at treeline is ~90cm. A thin crust on steep solar aspects has been buried by 5-10cm of new snow.

The base of the snowpack consists of weak, sugary facets and may collapse in shallow, rocky zones, producing large "whumpfs". Snow depth increases with elevation but distribution is highly variable; expect many rocks/trees lurking at and just below the snow surface.

Weather Summary

Warm air aloft will arrive Tues, with a hot pocket sitting between 2000-3000m. Temps will be below 0*C at valley bottom, while rising to +3*C in the Alpine. Winds are expected to be 40-65kph from the West.

The warm pocket will diminish Wed, with normal temps and light snow forecasted.

Detailed weather forecasts can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.

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.