Moderate storm for Sunday. Some increased danger, but manageable with good terrain selection.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Sunday: 10 cm/mm or so of snow/rain depending on elevation. Freezing level expected to be around 1400 m. Winds westerly 40-60 km/h. Monday: mostly dry until the late afternoon/evening. Winds light during the day, but picking up to become strong southwesterly in the afternoon. Monday night/Tuesday: A storm is expected to bring another 10 cm/mm of snow/rain with freezing levels around 1700 m and strong southwesterly winds.
Avalanche Summary
No new avalanches reported. See MIN (Mountain Information Network) posts for avalanche activity during the last storm.
Snowpack Summary
New storm slabs are starting to develop in the alpine as 5-10 cm of new snow arrived on Friday. High freezing levels (around 1800 metres) has settled the upper snowpack and developed variable crusts due to overnight cooling. New surface hoar has been reported from the Coquihalla area, that may be buried down 10-20 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. and it does not appear to "bridge" the early January weak layer in the Duffey lake area. This deeply buried persistent weak layer from early January appears to be isolated to the north of the region, and is now buried down about 50-80 cm. This layer continues to produce sudden results in snowpack tests and has been responsible for recent destructive avalanches.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.