Avalanche Forecast

Issued: Jan 20th, 2019 3:16PM

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

dsaly, Avalanche Canada

South Rockies.

Watch for fresh winds slabs and avoid shallow spots where triggering deeper layers is more likely.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

SUNDAY NIGHT: Mainly cloudy with isolated flurries, trace to 5 cm. Light north-northwest wind. Alpine low -10C.MONDAY: Mix of sun and cloud. Light northwest-west wind. Alpine high temperature -8C, freezing level 1000 m.TUESDAY: Cloudy with isolated flurries, trace accumulation. Moderate to strong west wind. Alpine high -10C.WEDNESDAY: Cloudy with scattered flurries, trace to 10 cm accumulation. Light to moderate west wind. Alpine high -6C, freezing level 1500 m.

Avalanche Summary

No recent avalanches have been reported. Skier traffic produced a few small (size 1) avalanches in the new snow on Thursday.The most recent reports of larger avalanches are from last weekend, when warm temperatures stressed the deeper layers in the snowpack and produced a few size 2 avalanches.

Snowpack Summary

Winds are redistributing up to 20 cm recent snow and building wind slabs in the alpine and treeline. This new snow is burying large surface hoar crystals and/or sun crusts, which could eventually develop into a touchy problem as snow accumulates. The most suspect terrain features will be steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist). Large variability in snow depths still exists in the region, ranging from almost no snow to nearly 200 cm in some areas. For average snowpack areas, expect to find weak and sugary faceted snow around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack has been the culprit for large avalanches in the region over the past few weeks.

Problems

Wind Slabs

Snow has accumulated above weak surface hoar and/or crusts and being redistributed by wind. The deepest and more reactive deposits will be in wind-loaded terrain features.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Deep Persistent Slabs

Deeply buried weak layers remain a concern. These layers are more easily triggered in areas where the snowpack is shallow, such as near ridges and rocky terrain.

Avoid steep, rocky terrain or shallow snowpack areas where triggering is more likely.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 21st, 2019 2:00PM