Avalanche Forecast

Issued: Jan 30th, 2016 7:54AM

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

rbuhler, Avalanche Canada

South Columbia.

A recently formed storm slab and touchy persistent weak layers are making for tricky conditions. Conservative terrain selection is critical.Use extra caution on steep south-facing slopes if the sun is out in force strength in the afternoon.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A mix of sun and cloud is expected for Sunday with light intermittent flurries possible. Freezing levels are expected to fall to valley bottom overnight and climb to around 1000m on Sunday afternoon. Alpine winds are forecast to be light from the northwest. Light snowfall is forecast for Monday but less than 5cm is expected. Freezing levels are expected to reach around 1000m on Monday and alpine winds are forecast to be moderate from the northwest. Similar conditions are expected for Tuesday with light snowfall, cool temperatures, and moderate northwest winds.

Avalanche Summary

On Friday, widespread natural avalanche activity up to size 3 was reported in throughout the region. This includes both storm slabs releasing down 30-60cm and persistent slabs failing down 70-100cm on the early January surface hoar layer. The storm slabs were failing on all aspects from 2000 to 2500m while the persistent slabs were failing on a variety of aspects around 1500-1900m. One persistent slab was also reported from 2300m on a southwest aspect. A skier accidently triggered a size 2 persistent slab avalanche on an east aspect at 1600m on the early January surface hoar layer down 70-80cm. Ski cutting also produced a few size 1-2 storm slab avalanches typically 20-30cm thick but one was 60cm thick. Natural activity is generally not expected on Sunday but could be possible on steep south facing slopes if the sun comes out in full strength in the afternoon. Recently formed storm slabs and a reactive persistent slab are both expected to be sensitive to human-triggering on Sunday.

Snowpack Summary

Recent storm loading brings storm slab thickness to around 20-40cm and up to 50cm in wind loaded areas. The recently destructive persistent weak layer from early January is now typically down 70-110cm in most places and continues to produce hard but sudden results in snowpack tests. The overlying slab remains primed for triggering and is especially touchy at and below treeline. The lower snowpack is well settled and strong below this layer.

Problems

Storm Slabs

Recently formed storm and wind slabs remain sensitive to human triggers. Weaknesses may exist within or below the storm snow.

Be cautious as you transition into wind affected terrain. >The new snow will require several days to settle and stabilize.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Surface hoar buried at the beginning of January remains reactive to human triggers. The potential for widespread propagation and remote triggering makes this persistent slab problem particularly tricky to manage.

Avoid steep open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Use conservative route selection and be aware of the possibility of remote triggering.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Jan 31st, 2016 2:00PM