Avalanche Forecast

Archived

Mar 1st, 2023–Mar 2nd, 2023

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Northwest Inland, Kispiox, Microwave-Sinclair, Ningunsaw, South Bulkley, South Bulkley, Telkwa.

The softest and safest riding can be found in the trees. Strong winds have hammered the snow surface at upper elevations. Reactive wind slabs may exist lower in start zones than usual. Be mindful that deep instabilities still exist and are most likely to be triggered from thin, rocky spots.

Confidence

Moderate

Avalanche Summary

Avalanche observations from this week have been limited to loose dry sluffing. Last week, several large deep persistent slab avalanches were reported in the alpine, including a natural size 3 near Kispiox, a cornice-triggered size 2.5 at Hudson Bay and several explosive controlled size 2-3 near Ningunsaw.

Looking forward, wind slab avalanches can be expected, with potential to step down to those deep instabilities, resulting in large, destructive avalanches.

Snowpack Summary

Extensive wind effect characterizes the snow surface at upper elevations. Wind slabs may be found sitting unusually low down in start zones and lees. Many exposed windward aspects have been scoured. In sheltered areas, 40-50 cm of recent snow may be sitting over a layer of small facets.

Several other crusts, layers of facets, or surface hoar can be found in the top 150 cm of the snowpack, but are not of great concern at present.

The lower snowpack consists of weak, basal facets which may become active with any rapid change or shock to the snowpack, such as heavy loading or dramatic warming. Snowpack depths range from 60 to 280 cm at treeline.

Weather Summary

Wednesday night

5-10 cm new snow. Strong southwest wind easing. Alpine low -10 ºC.

Thursday

Around 5 cm new snow. Wind easing to light southwest. Alpine high -8 ºC.

Friday

A mix of sun and cloud. Light southerly wind. Alpine high -12 ºC.

Saturday

Mostly sunny. Light easterly wind. Alpine high -10 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
Stay off recently wind loaded slopes until they have had a chance to stabilize.
Keep your guard up at lower elevations. Wind slab formation has been extensive.
Be mindful that deep instabilities are still present and have produced recent large avalanches.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.