Avalanche Forecast

Issued: Jan 22nd, 2019 4:37PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. 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 - Freezing levels are uncertain on Friday

Weather Forecast

TUESDAY NIGHT: Flurries, trace to 5 cm. Light west-northwest wind. Alpine low -10C, freezing level valley bottom.WEDNESDAY: Cloudy with scattered flurries, trace accumulation. Light to moderate west wind. Alpine high -6C, freezing level 1100 m.THURSDAY: Cloudy with sun and isolated flurries, trace accumulation. Light west-northwest wind. Alpine low -10C, rising freezing level.FRIDAY: Mainly cloudy with isolated flurries, trace accumulation. Light to moderate west-southwest wind. Alpine high -3C, freezing level rising above 2000 m.

Avalanche Summary

A size 1.5 natural wind slab avalanche was observed in steep terrain on Sunday. Skier traffic produced a few small (size 1) avalanches in the new snow on Thursday.The most recent reports of larger avalanches are from over a week ago, when warm temperatures stressed the deeper layers in the snowpack and produced a few size 2 avalanches.

Snowpack Summary

Strong winds have redistributed snow into thin winds slab in alpine lees and scoured wind-ward areas. In more sheltered alpine terrain and between 1600-2000 m, 5-15 cm recent snow overlies a layer of weak surface hoar and crusts (on solar aspects). 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

Recent snow fell on weak surface hoar and/or crusts. Wind continues to redistribute loose snow, expect the deepest and more reactive deposits will be in wind-loaded areas.

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.Be cautious on convex rolls around treeline where buried surface hoar may be preserved.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

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. Be very suspicious of steep slopes that have yet to avalanche this winter.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 23rd, 2019 2:00PM