Avalanche Forecast
Regions: Coquihalla, Harrison-Fraser, Manning, Skagit.
Wind slabs are the main concern. Keep in mind you may find them on a variety of aspects with recent shifting winds.
Confidence
Moderate
Avalanche Summary
Reports from Thursday confirm a natural avalanche cycle occurred in the Coquihalla area Monday night and Tuesday. Avalanches were reported as size 2-3 wind slabs, storm slabs and persistent slabs on northwest, northeast and southeast aspects in the alpine and treeline elevation bands. The persistent slab avalanches were suspected to have run on the facet/crust layer buried in mid-January (outlined in the avalanche problem section).
Please continue to post your reports and photos to the Mountain Information Network.
Snowpack Summary
Northeasterly winds have redistributed 20-40 cm of new snow and formed stiff wind slabs in exposed areas. In sheltered areas, surface faceting due to cold temperatures and/or soft surface snow may remain.
A melt-freeze crust formed in mid-January is buried up to 90-140 cm deep. In some areas, small faceted crystals can be found above the crust. This layer has been reactive during the storm Tuesday night and Wednesday this week. The snow below this layer is well consolidated.
Snowpack depths are just below seasonal averages. Total amounts range from 150 to 300 cm at treeline, but decreases significantly below 1500 m.
Weather Summary
Thursday night
Clear periods. Alpine temperatures drop to a low of -19 °C. Ridge wind northeast 15 km/h. Freezing level at valley bottom.
Friday
Sunny with cloudy periods. Alpine temperatures reach a high of -9 °C. Ridge wind southwest 10-25 km/h. Freezing level at valley bottom.
Saturday
A mix of sun and cloud with isolated flurries. Alpine temperatures reach a high of -6 °C. Ridge wind southwest 20 km/h gusting to 40 km/h. Freezing level at valley bottom.
Sunday
Cloudy with snowfall, 5-15 cm of accumulation. Alpine temperatures reach a high of -3 °C. Ridge wind southwest 30 km/h gusting to 75 km/h. Freezing level: 700 metres.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
25-45cm of new snow that fell on Monday and Tuesday has been redistributed by southwest and most recently northeast winds. Wind slabs may exist on all aspects in exposed areas and will have likely decreased in reactivity with recent cold temperatures.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
A crust formed in mid-January can be found down 80 to 120 cm. In areas around the Coquihalla facets can be found sitting on the crust. This layer is of greatest concern with large triggers, such as a cornice fall, or by first triggering a smaller avalanche that could step down to this interface.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1 - 3