Avalanche Forecast
Regions: Coquihalla, Manning, Skagit.
Wind and light snowfall are maintaining the wind slab problem and elevating the risk of triggering underlying weak layers. Choose simple avalanche terrain that avoids overhead hazard.
Confidence
Moderate
Avalanche Summary
On Friday, a large (size 2) glide slab avalanche was observed near the Coquhalla summit. Otherwise, no new avalanches have been reported since Tuesday's report that included a few skier and machine-triggered size 2 (large) persistent slabs in the Coquihalla corridor. An observation flight also confirmed a widespread natural avalanche cycle took place at the end of last week with avalanches reaching size 3 (very large).
Snowpack Summary
Light new snow amounts of up to 5 cm and a new melt-freeze crust (on steep solar aspects) make up the surface conditions. 60-100 cm of old storm snow continues to settle above a problematic facet/surface hoar/crust layer buried beneath it. This layer has acted as the failure plane in many recent avalanches in this region and adjacent regions and it continues to produce whumpfs and concerning snowpack test results at treeline.
In some areas a second, thicker crust with weak facets above either replaces or is buried just below the layer described above. It similarly continues to produce concerning snowpack test results and may also have been involved in some of the region's recent avalanche activity.
Weather Summary
Saturday night
Cloudy with 5-10 mm of precipitation. 60-75 km/h southwest alpine winds. Treeline temperature 1 °C with freezing level 2000 m falling to 1200 m.
Sunday
Mainly cloudy with isolated flurries 1-5 cm of new snow. 90 easing to 40 km/h southwest alpine winds. Treeline temperature -2 °C with freezing levels around 1200 m.
Monday
Cloudy with flurries bringing 1-5 cm of new snow. 40-60 km/h south alpine winds. Treeline temperature -2 with freezing level around 1200 m.
Tuesday
Cloudy with snowfall bringing 5-15 cm of new snow. 40-50 km/h south alpine winds. Treeline temperature -2 with freezing level around 1200 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Remote triggering is a concern, watch out for adjacent and overhead slopes.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Avalanche Problems
Persistent Slabs
Buried weak layers are most concerning at treeline elevations. Small avalanches may step down to this layer resulting in very large, destructive avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1.5 - 2.5
Wind Slabs
Recent storm snow may still react as a slab in wind affected features at higher elevations. Watch for deeper and more reactive slabs near ridgelines.
Expect new wind slabs to form as the southwest winds have increased.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2