Avalanche Forecast

Issued: Feb 26th, 2020 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

Wind loaded pockets of snow may sit on a weak interface. Caution around wind loaded ridgetops in the alpine and on convexities at upper treeline elevations.

Summary

Confidence

Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.

Weather Forecast

Wednesday night: Scattered flurries bringing a trace of new snow. Moderate southwest wind. Freezing level 1100 m.

Thursday: Scattered flurries bringing a trace of new snow. Moderate southwest wind. Freezing level 1400 m.

Friday: Mix of sun and cloud. Light to moderate southwest wind. Freezing level 1600 m in the north, 2000 m in the south.

Saturday: Around 5 cm new snow. Light to moderate southwest wind. Freezing level 1400 m.

Avalanche Summary

Some minor snowballing observed on steep sunny slopes Wednesday. A few skier controlled wind slabs up to size 1.5 were reported Tuesday. Natural and skier triggered wind slab avalanches were observed on northeast to west aspects in the alpine size 1.5-2 on Monday. We have not received reports of avalanche activity in the south of the region.

Snowpack Summary

15-30 cm of recent snow, and as high as 50 cm in the Coquihalla, may overly isolated patches of surface hoar in sheltered areas or sun crusts on solar aspects. Wind slab formation has been variable through the region. Extensive wind slab development has been reported in the western reaches of the region, and is suspected in the Coquihalla. In the northeast of the region, wind loading may be isolated to soft slabs in immediate lees in the alpine.

In the north part of the region (ie. Duffey/Hurley/Goldbridge), a deep instability exists at the base of the snowpack. It has not produced recent avalanche activity, with the most recent event on February 17. Rapid warming or heavy loading by new snow/wind/rain eventsĀ 

Terrain and Travel

  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Brief periods of sun could quickly initiate natural avalanche activity.
  • Surface hoar distribution is highly variable. Avoid generalizing your observations.
  • Investigate the bond of the recent snow before committing to your line.

Problems

Wind Slabs

An icon showing Wind Slabs

Wind effect has been variable through the region. In the northeast of the region, wind loading may be isolated to soft slabs in immediate lees in the alpine. More extensive wind slab development has been reported in the western reaches of the region, and is suspected in the Coquihalla. Wind slabs may sit over a weak interface, particularly around treeline.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

In the north of the region (e.g. Duffey, Hurley, Goldbridge), a buried weak layer lingers at the base of the snowpack. This layer has been quiet, with no reports of avalanches on it since mid February. There is potential for it to wake up with rapid warming or significant loading by new snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2.5 - 3.5

Valid until: Feb 27th, 2020 5:00PM