Avalanche Forecast
Issued: Jan 31st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Cornices.
jfloyer,
Avalanche Canada
While natural avalanches will become less likely, human-triggering remains a concern. Ease into terrain carefully after the storm ends.
Summary
Confidence
Weather Forecast
Friday night: 5-10 cm new snow with strong southwesterly winds becoming northwesterly by early morning. Freezing level 700 m.
Saturday: Flurries and light snow, 5-10 cm. Alpine high temperature -7 C. Strong westerly winds.
Sunday: Mix of sun, cloud, and isolated flurries. Alpine high temperature -10 C. Light southwest wind occasionally gusting to strong.
Monday: Mix of sun and cloud. Alpine high temperature -9 C. Light westerly winds.
Avalanche Summary
On Friday, natural storm snow avalanches were noted up to size 2 in steep south and southeast facing terrain at below treeline elevations. Loose wet avalanches were also observed.
On Thursday, a widespread avalanche cycle occurred up to size 2.5.
While natural avalanche activity is likely to taper off as we enter the tail end of the storm, human-triggering will remain possible in many areas.
Snowpack Summary
50-70 cm recent storm snow has been heavily impacted by strong southwesterly winds forming reactive storm slabs. This new snow overlies a variety of wind affected surfaces in exposed treeline and alpine areas.
Snowfall from the second half of January over lies a thin layer of facets, down 70-140 cm, that formed during the mid-January outflow event. Recent avalanche activity in the Bear Pass area and snowpack tests results have indicated that this layer is still a concern (check out this MIN report). Below tree line, a recent warm-up moistened snow surfaces up to 900 m, forming a temperature crust.
A crust from mid November lurks at the base of the snowpack. The last reported avalanche on this layer was Jan 17th. While it is promising that last week's significant snowfall did not trigger avalanches on this deep persistent weak layer, there is lingering uncertainty as to whether this week's weather could meet the threshold.
Terrain and Travel
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
Heavy snowfall with strong to extreme winds developed a widespread, reactive storm slab problem. Expect these slabs to be more pronounced in areas where strong winds are drifting the snow into deeper, stiffer, and more touchy slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A layer of weak, faceted snow from the previous cold snap is now buried 70-140 cm deep. Snowfall and wind are adding a rapid load this persistent weak layer, potentially bringing it to its tipping point. Smaller storm slab avalanches have the potential to step-down to this layer resulting in very large, destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornice grown has been noted in this region along exposed ridgelines, particularly on northeast aspects.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Feb 1st, 2020 5:00PM
