Avalanche Forecast

Issued: Jan 24th, 2019 4:01PM

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

dboucher, Avalanche Canada

North Columbia.

Warmer temperatures and rising freezing levels starting late Friday will make a more cohesive, easier-to-trigger slab above the weak interface. Pay attention to rapid change to snow surface with temperature warming and direct solar radiation.

Summary

Confidence

Moderate - Freezing levels are uncertain on Saturday

Weather Forecast

THURSDAY NIGHT: Mainly cloudy with isolated flurries, moderate west winds, alpine temperature -7 C, freezing level at valley bottom.FRIDAY: Cloudy with isolated flurries, moderate west winds, alpine temperature -2 C, freezing level at 1100 m.SATURDAY: Mainly cloudy with isolated flurries, moderate to strong west winds, alpine temperature around 0 C, freezing level rising up to 1800-2000 m with a weak temperature inversion.SUNDAY: A mix of sun and clouds with isolated flurries, moderate to strong northwest winds, alpine temperature -2 C, freezing level at 1200 m.

Avalanche Summary

Several storm slabs and persistent slabs avalanches up to size 2 triggered by people have been reported on all aspect at treeline and below on Wednesday.Â In the alpine, size 2 wind slabs avalanches have been triggered remotely on east and northeast slopes.Â All those avalanches ran on the buried surface hoar and crust interface which is now 20 to 40 cm below the surface.

Snowpack Summary

20-35 cm of snow sits above a layer of large surface hoar crystals and sun crust. In areas that have had wind effect the recent snow has been settling into a thin but reactive slab above this weak layer, with enhanced reactivity noted at elevations between 1500-1800 metres. In sheltered areas the snow lacks cohesion above this layer and is only reactive as dry loose sluffing. Expected warmer temperatures starting late Friday will change this and promote increased cohesion in the upper snowpack.The middle and lower portions of the snowpack are generally well-settled and strong.

Problems

Persistent Slabs

20-35 cm of snow sits above a weak interface of surface hoar and sun crust. Where the snow has formed a cohesive slab it is reactive to human triggering, especially between 1500m-1800m. Sluffing can be expected where there is not a slab.

Be cautious around open terrain features, such as cutblocks, gullies, and cutbanks.Watch for signs of instability such as whumpfing, cracking and recent avalanches..Expect to find deeper, reactive wind slabs as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 25th, 2019 2:00PM