Avalanche Forecast

Issued: Jan 26th, 2019 5:12PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Deep Persistent Slabs and Wind Slabs.

cgarritty, Avalanche Canada

South Rockies.

Our deep persistent slab problem may grow less likely to trigger in the coming days, but it isn't going away. Maintain diligent, cautious terrain selection that keeps you clear of thin spot trigger points and big overhead hazards.

Summary

Confidence

High -

Weather Forecast

Saturday night: Mainly cloudy. Strong west winds, increasing to extreme in the alpine.Sunday: A mix of sun and cloud. Strong northwest winds easing over the day. Alpine temperatures around -5 and cooling over the day. Freezing level to 1400 metres.Monday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures around -9 with freezing level back to valley bottom.Tuesday: Mainly sunny. Light west winds. Alpine high temperatures around -7.

Avalanche Summary

Recent avalanche observations have been limited to small (size 1), thin slabs released with ski cutting.

Snowpack Summary

Strong winds are stripping the last loose snow available and packing it into thin winds slab in alpine lees and scoured windward areas. Northwest winds have had some of the most recent impact on snow redistribution, creating 'reverse loaded' pockets of wind slab.In sheltered alpine terrain and between 1600-2000 m, 5-15 cm of recent snow overlies a layer of weak surface hoar and crusts (on solar aspects). 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

Deep Persistent Slabs

Deeply buried weak layers are an increasing concern with substantial warming and sun in the forecast. These deep layers are more easily triggered in areas where the snowpack is shallow, such as near ridges and rocky terrain.

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

Wind Slabs

Wind continues to redistribute loose snow into wind slabs at higher elevations. Expect to find the deepest and most reactive pockets in immediate lee areas near ridgecrests and around wind-exposed 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.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

Valid until: Jan 27th, 2019 2:00PM