Avalanche Forecast
Issued: Feb 6th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
kdevine,
Avalanche Canada
Persistent slab avalanches can be difficult to predict, so a conservative approach is recommended.
Storm slabs may still be easy to trigger, especially in wind loaded areas. Watch for a change in wind loading patterns with northerly winds.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
SATURDAY NIGHT - Mainly cloudy with isolated flurries / moderate northwest wind / alpine low temperature near -12Â
SUNDAY - Sunny with cloudy periods / moderate to strong northwest wind / alpine high temperature near -12
MONDAY - Mainly sunny / light to moderate northwest wind / alpine high temperature near -16
TUESDAY - A mix of sun and cloud / moderate to strong northwest wind / alpine high temperature near -20
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Avalanche Summary
At the time of publishing, there was a report of one size 2 human triggered persistent slab avalanche on a north aspect at 1200 m on Saturday.
On Friday, numerous dry loose avalanches were reported up to size 2 during the storm in steep terrain.Â
On Thursday, reports indicated several small features were reactive up to size 1 on the surface hoar that was buried in late January. I suspect that once the persistent slab gains more cohesion and stiffens, this problem may become more widespread. Even a small avalanche can catch you by surprise and have enough mass to push you into a terrain trap below.Â
Snowpack Summary
40-80 cm of recent storm snow from the past week sits on a persistent weak layer. This persistent weak layer consists of surface hoar in locations sheltered from the wind, facets, and stiff wind affected snow at upper elevations (upper treeline and the alpine). At lower elevations, (lower treeline and below treeline), 10-30 cm of snow sits above isolated pockets of surface hoar and a crust that is more prominent on solar aspects.Â
The mid-pack seems to be well settled. Deep persistent layers appear to have mostly become unreactive, with the exception of the Bear Pass area and the far reaches south of Kitimat.Â
Terrain and Travel
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Watch your sluff: it may run faster and further than you expect.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
20-40 cm of new storm snow has slowly accumulated over the past few days. Changing wind directions may deposit deeper and stiffer slabs on multiple aspects. I suspect that anywhere the new snow feels stiff and more cohesive the slab may be more reactive, especially where it sits above a buried weak layer.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
40-80 cm sits above a buried weak interface that consists of surface hoar, facets, and/ or a crust. As the snow above this layer becomes more consolidated, the likelihood of avalanches may increase.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 7th, 2021 4:00PM
