Avalanche Forecast

The snowpack structure, with its mid- and lower-pack problems remain relevant, even if several days old.

On Saturday the Hurley was the bulls-eye for avalanche activity on persistent weak layers in the middle and bottom of the snowpack. Surface hoar on the Christmas crust was releasing naturally, intentially, remotely, and with direct human triggers on gentle slopes near treeline (1800 to 1900 m) with crowns up to 80 cm thick. Some natural avalanches size 3 to 3.5 and ran full path from the alpine to valley bottom.

Additionally Storm Slabs size 2 to 3 were reported releasing at the bottom of the storm snow. One large wind slab (size 2.5) involved the weak facets at the bottom of the snowpack.

On Friday, snowcats remotely triggered numerous size 2.5 persistent slab avalanches on surprisingly low angel terrain from up to 150 m away. Avalanches occurred on a crust covered by surface hoar found up to 1900 on north and easterly aspects. See MIN for good photos and more details.

Several skier-triggered storm slab avalanches were reported up to size 1.5 throughout the region.

Thanks for the observations and please continue to post your reports and photos to the Mountain Information Network. It is really helpful for forecasters!

The regions generally weak snowpack structure remains.

Last week's 20-30 cm of snow and southerly winds means wind slabs my linger. Below 1900 m there was a mix of rain and snow which is freezing into a crust.

Mid-pack: 50 to 70 cm down is a crust formed in late December. Between 1900 and 1700 m surface hoar can be found above this crust which was reactive with the new snow load on Friday. This crust varies in thickness throughout the terrain and elevation. Uncertainty remains about the robustness of this crust above 2100 m.

Lower-pack: There is a widespread weak layer of facets and depth hoar at the bottom of the snowpack. Snowpack depths around treeline are about 150-180 cm deep. The snowpack below treeline is very shallow and faceted.

Sunday Night: Treeline temperature -5 to -10 C. Freezing level around 1000 m. Dry. Mix of cloud and stars. Light southeast wind.

Monday: Trace to a few cm of new snow. Mostly cloudy. Freezing level steady around 1000 m. Treeline temperatures -2 to -5 C. Light southwest wind.

Nil to a few cm of new snow. Freezing level near 1000m. Mostly cloudy. Treeline temperatures -2 to -5 C. Light to moderate southwest wind.

Wind strengthens to moderate, strong at high elevations. Nil to a few cm of new snow. Freezing level near 1000m. Mostly cloudy. Treeline temperatures -2 to -5 C.

More details can be found in the Mountain Weather Forecast.

• Be mindful that deep instabilities are still present and have produced recent large avalanches.
• In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.