Avalanche Forecast

Issued: Jan 28th, 2019 4:45PM

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.

kdevine, Avalanche Canada

South Rockies.

Wind slabs are likely to be encountered at upper elevations and may be reactive to human triggering, especially in lee features.

Summary

Confidence

Moderate - The weather pattern is stable

Weather Forecast

MONDAYÂ NIGHT - Cloudy with clear periods / northwest winds, 10-20 km/h / alpine low temperature near -10TUESDAY - Mainly sunny with cloudy periods / southwest winds 10-30 km/h / alpine high temperature near -6WEDNESDAY - A mix of sun and cloudÂ / southwest winds 10-20 km/h / alpine high temperature near -7 THURSDAY - Cloudy with sunny periods / southwest winds, 20-30 km/h / alpine high temperature near -5

Avalanche Summary

No new avalanches were reported on Saturday or Sunday.

Snowpack Summary

10-15 cm of cold smoke arrived by surprise on Sunday night! 10-30 cm of recent snow overlies a weak layer of sun crusts on south facing slopes, and surface hoar (feathery crystals) in sheltered areas. Previous strong winds had formed wind slabs over this interface. These are likely to be susceptible to human triggers, and they may be difficult to see now with the new snow on top of them.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 was the culprit in several large avalanches in the region in the past few weeks.

Problems

Wind Slabs

Previous variable wind directions may mean that wind slabs formed on all aspects throughout the region. They will likely be most reactive where they sit on a surface hoar layer (sheltered locations).

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: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Deep Persistent Slabs

The bottom of the snowpack consists of weak facets and depth hoar (sugary snow). Triggering this layer is becoming less likely, but the consequences remain high as avalanches on this layer will be very large and destructive.

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 29th, 2019 2:00PM