Avalanche Forecast

Archived

Dec 9th, 2022–Dec 10th, 2022

Alpine

Natural and human triggered avalanches likely.

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 unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Sea To Sky, Brandywine, Homathko, Powell River, Spearhead, Tantalus.

With the new snow and strong wind avoid riding steep wind loaded slopes, or having them above you.

Confidence

Moderate

Avalanche Summary

A size 1.5 avalanche was triggered by skiers entering a wind loaded slope. Thanks for the MIN Ben!

Please keep sharing your observations via the MIN; it helps strengthen our information gathering!

Snowpack Summary

Surface: Around 20 to 30 cm of new snow, but also at or near the surface you can find wind scoured, wind pressed, and of course wind slabsUpper-pack: on shaded terrain at all elevations large surface hoar (up to 10 mm) and generally unconsolidated snow. The upper snowpack consists of 20-50 cm of light but settling snow.Mid-pack: 50 cm down (maybe 70 to 100 cm in deep wind loaded areas) is a late November crust, with soft facets above. This is likely the critical snowpack weakness. Professionals are concerned about the possibility avalanches still releasing at this deeper interface.

Total snow depths remain low for early December with 70 to 120 cm at treeline and up to 180 cm in the alpine. Much of the below treeline elevation band is below the threshold for avalanches.

Weather Summary

Friday NightNext system approaching with moderate to strong southeast wind. 10 to 20 cm of snow overnight. Treeline temperatures around -5 to -10 C.

SaturdayAnother 10cm and possibly as much as 15 cm. Moderate to strong southerly wind. Temperatures warming slightly with around -5 above treeline.

Sunday

Storm ends overnight. Clearing through the day so a mix of sun and cloud depending where you are. Steady temperatures around -5 near treeline and higher. Light northerly wind

Monday

Clear. Dry. Light northerly wind. Slightly cooler, especially at lower elevations.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

The best and safest riding will be on slopes that have soft snow without any slab properties.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.

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.