Avalanche Forecast

Issued: Feb 4th, 2017 4:45PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada cgarritty, Avalanche Canada

Avalanche danger is increasing as new snow accumulates. Stick to supported, low angle terrain and expect stability to deteriorate over the day.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Saturday night: Scattered flurries bringing approximately 5 cm of new snow. Winds light to moderate from the southeast.Sunday: Mainly cloudy with isolated flurries and approximately 5cm of new snow. Winds light to moderate from the southwest. Alpine temperatures around -11. Closer to -20 in the far north.Monday: Cloudy with flurries delivering another 5-10cm of new snow. Winds light from the east. Alpine temperatures around -17.Tuesday: Cloudy with sunny periods and isolated flurries with a trace of new snow. Winds light from the southwest. Alpine temperatures about -15.

Avalanche Summary

Reports from Friday don't yet take into account our new snow, but small wind slabs again proved reactive to skier traffic over the day. Reports from Thursday include a number of large natural cornice falls from north-facing alpine ridgetops. Although these failed to trigger slabs below, wind slabs were observed on Thursday releasing under skier traffic to Size 1. One notable report details a remote-triggered Size 1 persistent slab observed in the north of the region. Although it ran on a steep southerly slope and had a relatively shallow depth (20 cm), it was reported to have failed on our January 15 surface hoar and reinforces ongoing concerns for persistent slab problems in that part of the region. As for Sunday's outlook, fresh storm slabs are expected to be sensitive to light triggers, especially where they overlie weak layers present at our previous surface. In the north of the region around Blue River and Valemount, a persistent slab problem still exists and the potential for storm slab avalanches to 'step down' should be considered. Several large human triggered avalanches were reported last week. Click here for more details.

Snowpack Summary

Around 20 cm of new, low-density snow from Friday and Saturday has now buried a range of surface conditions that developed over the past week. Along with wind slabs that recently formed on a wide range of aspects, the new snow has also buried a sun crust that was reported on steep solar aspects as well as surface hoar found on sheltered open slopes in the days before the storm. Surface faceting was also reported as a result of cold temperatures over the week. The new snow will likely form a weak bond to these surfaces and touchy conditions can be expected as it accumulates into storm slabs above them. A persistent weakness buried mid January is now down 40-60 cm and consists of buried surface hoar in sheltered areas, and/or widespread faceted old snow. It has generally stabilized but may be sensitive to triggering in isolated areas where buried surface hoar is preserved.Another surface hoar/facet persistent weakness was buried mid-December and can now be found down 110-130 cm. It has become inactive in the south of the region, but may still be sensitive to triggers in the northern part of the region near Blue River and Valemount. Read the Cariboo forecast for more information.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs are forming over a weak layer of snow that was formed during recent clear weather. Expect the new snow to be especially touchy in wind-exposed areas.
Watch for signs of instability such as whumpfing, or cracking. Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Minimize exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Feb 5th, 2017 2:00PM