Avalanche danger is increasing with forecast new storms moving onto the coast.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
A series of Pacific disturbances are lining up to hit the coast over the next few days. Light-Moderate snowfall amounts are expected above the snow/rain line, and valley bottoms should be warm and rainy. The freezing level should stay around 1200 metres overnight and then rise to 1500 metres on Friday. Saturday morning should be a bit cooler as freezing levels drop down to about 900 metres and stay below 1400 metres all day. Warmer air associated with the Sunday storm should push freezing levels back up above 1700 metres. Heavy precipitation, strong southerly winds, and high freezing levels are forecast for Monday.
Avalanche Summary
No new avalanches reported. See MIN (Mountain Information Network) posts for avalanche activity during the last storm.
Snowpack Summary
Thin new crusts have formed on most aspects at higher elevations above moist snow, and above dry snow on northerly aspects. New surface hoar has been reported from the Coquihalla area, that may be buried down 5-10 cm. Conditions across the region are variable. Most areas have not had a freeze below treeline since the last wet storm. A crust that formed after a warm storm at the end of January is now down 50-80 cm. The deeply buried persistent weak layer from early January appears to be isolated to the north of the region. This weakness which lies between 60 and 130cm below the surface is still reactive at higher elevations in the Duffey, Hurley and Birkenhead areas. This layer continues to produce sudden results in snowpack tests and has been responsible for recent destructive avalanches.
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.
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.