Avalanche Forecast

On Sunday, a natural size 2.5 storm slab was observed in the south of the region at 1200 m which is expected to have failed on the weak layer of facets and surface hoar below the recent storm snow. A controlled size 2 storm slab was also reported which was 50 cm thick. In the north, a couple of natural size 1.5 storm slab avalanches were reported.

This MIN report from Saturday near Terrace includes reports of numerous small storm slab avalanches but also shows an avalanche stepping down to an older weak layer.

This MIN report from Sunday has a great photo showing the temperature inversion and the effect of the recent warm temperatures. As temperatures cool, a new surface crust can be expected at elevations that saw the recent warm air and/or rainfall.

The recent storm snow has buried a highly variable snow surface that had formed during the recent period of extended cold temperatures and outflow winds. This newly buried weak layer consists of widespread facets, patchy surface hoar in sheltered terrain, and heavily wind-affected surfaces in exposed terrain including wind-scoured and wind-pressed surfaces, old hard wind slabs, and sastrugi.

A layer of large surface hoar crystals, buried in early December, was found down 20 to 50 cm prior to the storm. This layer has previously produced small but remotely-triggered avalanches.

The lower snowpack is well consolidated below a crust that had formed in mid-November which can be found below around 1200 m elevation.

Both the early-December surface hoar and mid-November crust have been dormant recently but could wake up with the new load from the storm snow, and avalanches have the potential to step down to these deeper layers.

Monday night

Snowfall 10-20 cm, moderate to strong SW wind, freezing level around 1000 m.

Tuesday

Mainly cloudy in the morning, sunny breaks in the afternoon, light to moderate NE wind, freezing levels generally falling to around 500 m or lower.

Wednesday

Mainly cloudy with a chance of light flurries, light to moderate SW wind, treeline high around -3 °C.

Thursday

Cloudy with light snow, moderate to strong SE-S wind, treeline high around -5 °C.

More details can be found in the Mountain Weather Forecast.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Be alert to conditions that change with elevation and sun exposure.