Avalanche Forecast

Issued: Jan 25th, 2015 8:37AM

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

pgoddard, Avalanche Canada

South Rockies.

It's too warm for winter. Eye the snowpack with suspicion until the weather returns to normal.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

No precipitation, very warm temperatures (freezing level above 3000 m) and strong SW winds continue until late Tuesday/ Wednesday, when the freezing level drops to around 2000 m and winds become light.

Avalanche Summary

Recent natural wind-triggered slabs of size 1-2 were observed in the Elk Valley on Saturday on lee and cross-loaded slopes. Cornices were also building. In the SE of the region, a natural size 2 slab failed on the Dec crust at 1800 m on a south aspect. Loose wet natural avalanches to size 1.5 were also observed.Nearby in the Lizard region, there have been several concerning human-triggered avalanches on the mid-Dec layer and two very large avalanches on the Nov persistent weak layer. Check the Lizard/Flathead bulletin for more info. Until we have more observations from the South Rockies to build our confidence, assume that further deep persistent slab avalanches are possible, especially while experiencing unseasonably warm temperatures for the next few days.

Snowpack Summary

Moderate-to-strong SW winds may continue to redistribute snow in the high alpine and load leeward features. In sheltered areas, 10-20cm of rapidly settling snow overlies a rain crust to 1900m, facets, and/or surface hoar. The mid-December crust/facet layer is down 40-80cm. Tests indicate that this layer is still reactive in some areas. Isolated large avalanches continue to release on this interface. In shallow snowpack areas, the mid-December crust is breaking down through the faceting process. Closer to the ground a crust/facet interface that formed in November is generally dormant but may still be reactive in isolated areas. In some places the basal snowpack consists entirely of sugary facets. Below treeline, the snowpack is shallow and weak in many places.

Problems

Deep Persistent Slabs

The likelihood of triggering a deep slab may remain elevated while the temperatures stay unusually warm. A surface avalanche or cornice fall could step down to a deeper layer, creating a very large avalanche.

Avoid convexities or areas with a thin or variable snowpack where triggering could be more likely.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Loose Wet

Be aware of slopes above you that may be cooking in the sun - these may avalanche. Generally warm temperatures may mean that wet avalanches are possible on all steep slopes.

Cornices become weak with heating, so give them a wide berth.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>Be cautious of loose wet or wet slab sluffing in steep terrain.>

Aspects: North, North East, East, South East, South, South West.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Wind Slabs

Recent winds have shifted snow into wind slabs on lee and cross-loaded slopes. These may fail with the weight of a person or snowmobile,

Be cautious as you transition into wind affected terrain.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 26th, 2015 2:00PM