Avalanche Forecast

High

It was a busy day for avalanche activity in the region with almost all operators reporting some variation of the theme of a natural and skier-triggered avalanche cycle as 40-70 cm of new snow settled into touchy storm slabs in some areas and produced powerful dry loose releases where slabs hadn't quite formed. Savvy terrain use kept most releases small, however large audible avalanches are peppered throughout Sunday's reports.

Clear skies last week allowed for observations of many deep persistent slab avalanches as well as explosive control missions, which produced large to very large (size 2 to 3.5) avalanches. They were on all aspects and between 2200 m and 2800 m in elevation. Although many of the avalanches occurred in unrideable terrain, they are evidence that the weak basal snowpack is still triggerable. Riders should continue to avoid thin snowpack areas, which are often found near ridgelines.

Looking forward, storm slabs from the weekend may remain sensitive to human triggering a bit longer than usual, owing to the weak faceted snow they overlie. Otherwise we expect surface instabilities to gradually become more focused toward wind loaded areas.

Stormy conditions over the weekend brought up to about 40-80 cm of new snow to the Monashees, closer to 20-50 cm in the Selkirks, along with strong southwest wind. The new snow buried an interface from the recent cold period which includes faceted (sugary) surface snow, small surface hoar in sheltered areas, and widespread heavy wind effect and wind slabs in exposed terrain from recent northeast winds. Below this interface is 20-50 cm of older storm snow from the beginning of last week.

Around 100 to 130 cm of snow may now rest on a small layer of surface hoar crystals that was buried mid-February. This layer is most likely found around treeline elevations in areas sheltered from the wind. This layer generally appears to be dormant now but could still be capable of producing avalanches in isolated areas. The remainder of the mid-snowpack is generally strong.

A layer of large and weak facets that formed in November is deeply buried, found near the base of the snowpack. The likelihood of human triggering this layer is currently low given its depth. However, it is still best to avoid steep, thin, rocky slopes near ridges at alpine and upper treeline elevations.

Monday night

Mainly cloudy with isolated flurries. Light southeast winds.

Tuesday

Mainly cloudy with isolated flurries. Light east or southeast winds. Treeline high temperatures around -8 °C.

Wednesday

Cloudy with isolated flurries, increasing overnight. Light west winds shifting southwest and increasing. Treeline high temperatures around -8.

Thursday

Cloudy with continuing snowfall bringing 10-25 cm of new snow, greatest in the north of the region. Moderate southwest winds. Treeline high temperatures around -7.

More details can be found in the Mountain Weather Forecast.

• Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
• Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.