Avalanche Forecast

Archived

Mar 10th, 2023–Mar 11th, 2023

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 possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

North Columbia, South Columbia, Esplanade, Jordan, North Selkirk, Shuswap, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan.

Strong northeasterly winds have formed fresh wind slabs on lee aspects in the alpine.

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

Confidence

High

Avalanche Summary

A cornice triggered size 3 deep persistent slab avalanche was reported on the northeast face of Mt. Mackenzie on Thursday. See MIN.

Explosive control work on Thursday triggered wind slabs up to size 2 on steep, wind loaded alpine slopes.

One explosive triggered size 2.5 was reported east of Revelstoke on a wind loaded, large alpine slope. It released on weak layer around 100 cm deep.

Snowpack Summary

Sun crust on sunny slopes and surface hoar (3-10 mm) on shady slopes at all elevations. Previous wind effect in open areas at treeline and above.

The mid-snowpack is generally strong but the lower snowpack is a different story. The November facets are still prominent at the base of the snowpack. They are showing signs of rounding but there is still a considerable step in resistance between them and the overlying snow. These facets are most pronounced in shallow rocky areas.

Weather Summary

Friday Night

Cloudy with isolated flurries; 0-5 cm / Light southwest ridgetop wind / Low temperature at treeline around -10 C / Freezing level valley bottom.

Saturday

Cloudy with flurries; 3-10 cm / Light southwest ridgetop wind / High temperature at treeline around -3 C / Freezing level 1000 m.

Sunday

Mostly cloudy with isolated flurries; 3-5 cm / Light south ridgetop wind / High temperature at treeline around -2 C / Freezing level 1300 m.

Monday

Snow; 10-20 cm / Strong southwest ridgetop wind / High temperature at treeline around 1 C / Freezing level rapidly rising to 1800 m.

More details 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.
Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Avalanche hazard may have improved, but be mindful that deep instabilities are still present.

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.