Avalanche Forecast

Issued: Jan 27th, 2019 4:39PM

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.

Concern remains for the weak layers that exist near the base of the snowpack. These deep persistent weak layers can be very difficult to manage, so a conservative approach to terrain is recommended.

Summary

Confidence

Moderate - The weather pattern is stable

Weather Forecast

SUNDAY NIGHT - Cloudy with clear periods / northeast winds, 15-20 km/h, gusting to 50 km/h / alpine low temperature near -14 MONDAY - A mix of sun and cloud / light west winds / alpine high temperature near -10TUESDAY - A mix of sun and cloud / light west winds/ alpine high temperature near -6 WEDNESDAY - A mix of sun and cloud / west winds, 10-30 km/h / alpine high temperature near -6

Avalanche Summary

No new avalanches were reported in the region on Saturday.Previous recent avalanche observations were limited to size 1 thin slabs that released with ski cutting.

Snowpack Summary

5-15 cm of recent snow overlies a weak layer of sun crusts on south facing slopes, and surface hoar (feathery crystals) in sheltered areas. Strong winds have stripped the new snow off of this layer in wind exposed areas and created deeper deposits in lee features. Wind slabs that have formed over this interface are likely to be more susceptible to human triggers.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

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

Be cautious on convex rolls around treeline where buried surface hoar may be preserved.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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.

Avoid steep, rocky terrain and 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 28th, 2019 2:00PM