Avalanche Forecast

Issued: Dec 22nd, 2018 4:03PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

mconlan, Avalanche Canada

South Coast Inland.

The highest snowfall amounts are for the south of the region. Observe for new slabs that may form with snow and strong winds. For the north of the region, be diligent around treeline, where a buried weak layer may still linger.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

SATURDAY NIGHT: Cloudy with snowfall, accumulation 10 to 15 cm, strong southwest winds, freezing level rising to 1000 m.SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate southwest winds, alpine temperature -5 C, freezing level 1000 m.MONDAY: Clearing over the day, light south winds, alpine temperature -6 C, freezing level 700 m.TUESDAY: A mix of sun and cloud, light northwest winds, alpine temperature -9 C, freezing level 500 m.

Avalanche Summary

A natural avalanche cycles occurred on Thursday in the north of the region, with large avalanches up to size 3. These avalanches ran within the storm snow as well as on the weak layer described in the snowpack summary.

Snowpack Summary

New wind slabs may form the storm today, which may sit on old wind slabs from Thursdayâ€™s storm. Below around 1800 m, expect to find a melt-freeze crust formed by rain from Thursdayâ€™s storm.In the north portion of the region and possibly the far south, a weak layer of facets and surface hoar lies below all this storm snow, around 100 to 150 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. While the layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists.Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover.

Problems

Wind Slabs

New wind slabs are expected to form due to snowfall and associated strong winds. Expect to find wind slabs in the lees of terrain features, and possibly elsewhere if enough snowfall accumulates.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind-loaded snow.

Aspects: North, North East, East, South East, West, North West.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer buried 100 to 150 cm has the potential to produce large avalanches. This layer is likely most problematic in the north of the region and possibly the far south, around treeline and lower alpine elevations.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Use conservative route selection and choose moderate-angled slopes with low consequence.Cornices are large and looming, and could trigger persistent slabs on slopes below.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 23rd, 2018 2:00PM