Bulletin d’avalanche South Columbia — Jan 30, 2015

Points saillants

The chance of triggering a persistent slab has decreased, but the consequences would be high.

Problèmes avalancheux

Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alpin
Limite forestière
Sous la limite forestière
Probabilité
Possible
Taille
2–5
A layer of surface hoar buried in the upper snowpack remains a concern, especially at treeline and higher. A large trigger, like an avalanche in motion or cornice fall, could also trigger a deeper persistent weakness.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

A few cm snow are forecast for Friday night. A second pulse of snow (5-15 cm) is due on Sunday, with another 5-10 cm on Monday. Freezing level is at valley floor. Winds are generally light for the next three days, rising to moderate westerly on Monday.

Avalanche Summary

There was a widespread avalanche cycle earlier in the week in response to the warm storm. Natural activity has now eased, but explosives were able to trigger several large slabs (some failing sympathetically with each other) up to size 3 on the January surface hoar layer on Thursday around 2200 m.

Snowpack Summary

New snow overlies variable crusts exist at most elevations, ranging from breakable to supportive. Generally small surface hoar sits on this crust. At the highest elevations, you might find some wind-affected snow and cornices. The mid-January surface hoar remains a concern and can be found down between 30 and 80 cm. In some locations it has reportedly gained quite a bit of strength, but in other spots it still produces sudden (pops) results in snowpack tests. The mid-December surface hoar layer is now 80 to 140cm below the surface and has become unlikely to trigger (but still has the potential for a large avalanche if triggered).

South Columbia

Danger d’avalanche