Avalanche Forecast

Issued: Jan 18th, 2019 4:48PM

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.

shorton, Avalanche Canada

South Rockies.

Watch for fresh wind slabs and avoid shallow spots where triggering deeper layers is most likely.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY NIGHT: Scattered flurries with localized accumulations of 5 cm, strong southwest wind, alpine temperatures drop to -10 C.SATURDAY: Mostly cloudy with isolated flurries, strong to extreme west wind, freezing level climbing to 1500 m, alpine high temperatures around -3 C.SUNDAY: Mostly cloudy with flurries possible later in the day, strong west wind, freezing level climbing to 1200 m, alpine high temperatures around -6 C.MONDAY: Skies clearing throughout the day, moderate north wind, alpine high temperatures around -6 C.

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

5-15 cm of 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 gradually accumulating above weak surface hoar and/or crusts. Wind loaded slopes may have enough snow above this layer for small avalanches.

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 - 1.5

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 slopes in 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 19th, 2019 2:00PM