Forecast sun and high freezing levels may increase the danger from loose wet avalanches and avalanches stepping down to the deeply buried weak layer.
Confidence
Fair - Timing or intensity of solar radiation is uncertain on Wednesday
Weather Forecast
Overnight and Wednesday: Clear overnight with freezing level down to valley bottom and light winds. Moderate Southwest winds and some cloud developing in the afternoon. Freezing level rising quickly to near 2500 metres.Thursday: Continued warm air in the alpine with moderate to strong Northerly winds developing during the day. Mix of sun and cloud during the day, clearing in the evening.Friday: Sunny and clear with strong Northwest winds and cooler temperatures.
Avalanche Summary
No new large avalanches reported. Some thin wind slab releases up to size 1.5 due to reverse loading were reported. Snow-balling and moist loose avalanches were reported from Southerly aspects. Extensive explosive control did not result in any releases on the deeply buried weak layer in the Coquihalla area on Tuesday.
Snowpack Summary
10-30 cm of cold low density new snow has fallen in the past couple days, accompanied by light to moderate W-NW winds. Older dense wind slabs may be lightly buried on a variety of aspects and in cross-loaded terrain features. In the southern portion of the region up to 200 cm of settled storm snow sits on a crust/facet combination buried in mid February. In northern sections this weakness includes surface hoar and is generally down 60-100 cm. Recent snowpack tests indicate that this weak layer may be gaining strength, but professionals remain suspect. The mid and lower snowpack are generally strong and well-settled. However, basal facets and depth hoar are likely to exist in the north of the region and still deserve respect on thin rocky alpine slopes.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.