Issued: Apr 26th, 2023 4:00PM
The alpine rating is Wind Slabs, Persistent Slabs and Cornices., the treeline rating is , and the below treeline rating is Known problems include
Wintry conditions are found in the alpine, whereas spring-like problems are prominent at lower elevations. Travel cautiously and be aware of the various avalanche problems you could come across.
Numerous human-triggered persistent slab avalanches have occurred on the layers described in the Snowpack Summary over the past few weeks. Continue diligent terrain travel to limit your exposure to this avalanche problem.
The likelihood of seeing very large avalanches releasing on the deeply buried weak layer near the base of the snowpack as described in the Snowpack Summary will increase with each day of warming. This is particularly true for days without an overnight surface refreeze. Humans are most likely to trigger these layer in steep and rocky slopes where the layer is closer to the snow surface.
Avoiding cornice exposure is also a good idea, as they are very large and could fail naturally or under the weight of a human.
Wind and storm slabs may have formed during Tuesday night's storm. This new snow overlies a melt-freeze crust on all aspects up to 1300 m and to ridgetop on sun-exposed slopes.
Various layers of surface hoar, facets, and crusts may be found around 50 to 150 cm deep in coastal areas and 30 to 50 cm in shallower snowpack areas in the north and east of the region.
Weak faceted grains may exist near the base of the snowpack, particularly in shallower snowpack areas.
Cornices are large and looming at this time of year and will weaken with daytime warming.
A cool and cloudy Thursday is expected with the freezing level around 1000 m and moderate southwest winds. Freezing levels are on the rise for Friday and into the weekend, ranging from 2000 m to 3300 m. A mix of sun and cloud is generally expected, with cloudy skies and rain on Sunday.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Use small low consequence slopes to test the bond of the new snow.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Cornice failures could trigger very large and destructive avalanches.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
Snow and strong wind have likely formed new wind slabs in lee terrain features at higher elevations. Assess for slabs in steep terrain before committing yourself.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Weak layers may be buried anywhere from 30 to 150 cm deep. Avoid steep open slopes capable of producing large avalanches. Numerous large persistent slab avalanches were triggered by riders in the alpine between April 10th and 12th.
Aspects: All aspects.
Cornices are large at this time of year and will become more prone to fail as they warm up with spring weather. Stay well back from them when on ridgelines and limit your exposure when travelling on slopes below them, as their release is unpredictable. Cornice falls could trigger very large slab avalanches on slopes below them.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Valid until: Apr 27th, 2023 4:00PM