Avalanche Forecast

Archived

Dec 17th, 2023–Dec 18th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

North Rockies, McBride, Sugarbowl, Kakwa, McGregor, Renshaw, Robson.

Start with small slopes, and gather information before heading into committing terrain.

Continue to be wary of a buried layer of surface hoar.

Confidence

Moderate

Avalanche Summary

On Saturday, west of Prince George, there were reports of natural and rider triggered avalanches up to size 2. It seems that avalanches were occuring at all elevations, but that they were most prominent in wind affected terrain in upper treeline.

See this great Mountain Information Network (MIN) post for one group's observations from the day.

We expect that human triggered avalanches will remain possible on Sunday.

Snowpack Summary

20-40 cm of recent snow is settling on old, hard surfaces, like windslabs or a frozen crust.

A concerning layer of surface hoar can be found 50-90 cm below the snow surface.

A crust with sugary facets beneath it can be found just above the ground. Average snowpack depths at treeline range from 65 to 100 cm.

Weather Summary

Sunday Night

Partly cloudy. Possible trace of snow expected. Light to moderate southwest ridgetop wind. Treeline high around -4°C with possible temperature inversion.

Monday

Cloudy. 2-5 cm of snow expected. Light southeast ridgetop wind. Treeline temperature around -2°C with possible temperature inversion.

Tuesday

Cloudy. 5-20 cm of snow expected (highest amounts just east of Prince George). Moderate to strong southwest ridgetop wind. Treeline temperature around -1°C with possible temperature inversion.

Wednesday

Mostly cloudy. 5-10 cm of snow expected. Light to moderate southwest ridgetop wind. Treeline temperature around -3°C with possible temperature inversion.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
Approach lee and cross-loaded slopes with caution.
Highmark or enter your line well below ridge crests to avoid wind loaded pillows.

Problems

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.

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.