Regions
Northwest Coastal.
Cornices remain the primary concern. Solar radiation is a common cornice trigger. Limit your exposure when it's cloudy and completely avoid cornices when it's sunny.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Unsettled weather and cool temperatures continue throughout the forecast period.TUESDAY: Cloudy with scattered flurries (5-10cm). Light southeast ridgetop winds. Freezing level around 1200 m.WEDNESDAY: Mix of sun and cloud with isolated flurries (0-5cm). Strong easterly ridgetop winds. Freezing level around 1500 m.THURSDAY: Mainly cloudy with isolated flurries (2-5cm). Moderate southeasterly ridgetop winds. Freezing level around 1400 m.
Avalanche Summary
On Sunday, several Size 2 wet slabs were triggered with explosives control work in the north of the region. Loose wet avalanches to Size 2 were also reported running naturally on solar (south facing) aspects.
Snowpack Summary
Small amounts of new snow (up to 10cm) fell in the past few days with light to moderate southerly winds. The new snow will likely be sitting on hard surfaces created by strong winds last week, or melt-freeze crusts below 1400m.Sunny breaks and warmer temperatures on Monday has likely left a supportive temperature crust on all aspects up to treeline. North facing alpine slopes reportedly have up to 10cm dry powder, on a firm crust. A weak layer of facets and crusts from late February are buried 100-120 cm down. The layer has been unreactive recently and has a variable distribution. That said, rapid warming of the snowpack or a large trigger, such as a cornice, may still have the potential to trigger it.
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.