Avalanche Forecast

Archived

Feb 20th, 2023–Feb 21st, 2023

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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

Cariboos, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, North Monashee, Renshaw, Robson.

Stormy conditions on Monday night will produce dangerous avalanche conditions for Tuesday.

Confidence

Moderate

Avalanche Summary

Small wind slabs were triggered by riders on Sunday as the recent snow was redistributed by wind.

On Saturday, explosives triggered a few large (size 2 to 3) deep persistent slab avalanches 200 cm deep on north to east aspects between 1900 and 2300 m.

Looking forward, large storm and wind slabs could be human-triggered within all the recent storm snow. Wind slabs could rapidly form on atypical aspects due to northeast wind on Tuesday.

Snowpack Summary

Monday night's storm snow will add to the 40 to 80 cm of recent storm snow, which may sit on a small layer of surface hoar crystals in wind-sheltered terrain. In wind-exposed terrain, the snow is being redistributed into wind slabs and large cornices. The wind was predominantly southwest but is switching to northeast, meaning that wind slabs may be found on all aspects.

The mid-pack is generally strengthening. A spotty surface hoar layer may be found about 80 to 150 cm deep. This layer is most likely found in openings around treeline elevations that are sheltered from the wind. The layer hasn't produced recent avalanches.

Large and weak facets that formed in November are found near the base of the snowpack. A cornice fall is a likely trigger for this layer.

Weather Summary

Monday Night

Cloudy with snowfall, accumulation 15 to 25 cm, 20 to 40 km/h southwest wind, treeline temperature -14 °C.

Tuesday

Mostly cloudy with isolated snowfall, accumulation 1 to 3 cm, 30 km/h northeast wind, treeline temperature -20 °C.

Wednesday

Mix of sun and cloud with no precipitation, 20 km/h northeast wind, treeline temperature -25 °C.

Thursday

Mix of sun and cloud with no precipitation, 20 km/h northeast wind, treeline temperature -26 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Travel in alpine terrain is not recommended.
Continue to make conservative terrain choices while the storm snow settles and stabilizes.
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.
Minimize your exposure time below cornices.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.