Avalanche Forecast

Issued: Jan 24th, 2015 8:46AM

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

pgoddard, Avalanche Canada

South Rockies.

While temperatures remain high, continue to be cautious in your route-finding and take a conservative approach. Surprisingly large avalanches are possible.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Minimal precipitation, very warm temperatures (freezing level above 3000 m) and strong SW winds are the name of the game until late Tuesday, when the freezing level drops and winds die out.

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 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 alpine and load leeward features. In sheltered areas, 10-20cm of 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; and 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. Below treeline, the snowpack is shallow and rotten in many places.

Problems

Deep Persistent Slabs

Sun and warming may increase the chances of triggering this beast, with high consequences. Sporadic deep releases over the last week are evidence that this problem is lingering.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Continue to give wind-loaded slopes a wide berth. These may look fat, smooth or bulbous, or be overhung with cornices. A wind slab or cornice fall could trigger a deeper weak layer.

Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Wet

Steep sunny slopes may burst into life on Sunday with a round of natural loose wet activity. A loose snow avalanche may trigger a deeper weak layer.

Minimize exposure to sun exposed slopes when the solar radiation is strong.>Cornices become weak with heating, so give them a wide berth.>

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Valid until: Jan 25th, 2015 2:00PM