Avalanche Forecast

Issued: Feb 4th, 2017 5:06PM

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: Flurries bringing 5-10 cm of new snow. Winds moderate from the southwest.Sunday: Cloudy with scattered flurries and approximately 5 cm of new snow. Winds moderate to strong from the southwest. Alpine temperatures of -10.Monday: Flurries delivering another 5-10 cm of new snow. Winds light to moderate from the south. Alpine temperatures of -13.Tuesday: A mix of sun and cloud with isolated flurries and a trace of new snow. Winds light from the southwest. Alpine temperatures of -15.

Avalanche Summary

Reports from Friday don't yet take into account our new snow, but loose snow sluffing (to Size 1) in steep terrain has been a developing theme this week, likely aided by recent faceting of surface snow. Reports from Thursday include a large natural cornice fall in the north of the region which succeeded in triggering a small slab, as well as evidence of wind slabs releasing both naturally and under skier traffic to Size 2.As for Sunday's outlook, fresh storm slabs are expected to be sensitive to human triggering, especially where they overlie weak surfaces and in wind exposed areas where slab properties will develop more quickly.

Snowpack Summary

Around 20 cm of new snow over Friday and Saturday has now buried a range of different conditions that existed at our previous surface. In addition to wind slabs that exist on a variety of aspects in exposed terrain, the new snow also overlies a sun crust reported on steep solar aspects as well as surface hoar recently found growing on sheltered open slopes. Surface faceting has also been reported as a result of the recent cold temperatures. The bond of the new snow to these underlying surfaces will likely be weak and touchy conditions can be expected as the new snow settles into storm slabs above them. A persistent weakness buried mid January is now down 30-60 cm and consists of buried surface hoar in sheltered areas, sun crust on south aspects, 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. The mid and lower snowpack are generally well settled and stable.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs will form over Friday night and Saturday. A wide range of weak surfaces will prevent the new snow from bonding well over the short term. Expect conditions to be especially touchy in wind-exposed areas
Choose well supported terrain without convexities.Watch for signs of instability such as whumpfing, or cracking. Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

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

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