Avalanche Forecast

Issued: Jan 19th, 2019 4:34PM

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

Low - Due to the number of field observations

Weather Forecast

SATURDAY NIGHT: Mostly cloudy with isolated flurries, trace accumulation. Moderate to strong west wind. Freezing level valley bottom, alpine low temperature -8C.SUNDAY: Mostly cloudy with flurries later in the day. Light northwest wind with moderate gusts. Freezing level climbing to 1200 m, alpine high temperature -6C.MONDAY: Overnight flurries with skies clearing throughout the day, around 5 cm accumulating by Monday morning. Light west-northwest wind. Freezing level valley bottom, alpine high temperature -8C.TUESDAY: Cloudy with sunny breaks. Moderate west wind. Freezing level valley bottom, alpine low temperature -13C.

Avalanche Summary

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

10-20 cm new snow is being redistributed by strong winds are forming 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

New snow is accumulating 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 convexities or areas with a thin or variable snowpack.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 20th, 2019 2:00PM