Confidence
Fair - Forecast snowfall amounts are uncertain on Saturday
Weather Forecast
A warm front is forecast to move over the central and south coast on Friday night, bringing moderate precipitation and strong westerly winds. The winds are expected to peak at about 100 km/hr sometime in the early morning. Expect about 5-10 cm of snow overnight and another 5-10 cm during the day on Saturday. The freezing level on Saturday should rise to about 1200 metres. Snow is expected to continue on Sunday bringing another 5 cm and strong westerly winds. Periods of heavy snowfall are expected on Monday.
Avalanche Summary
Several size 1.0 avalanches have been reported from the Duffey Lake area. As reports of natural activity have started to taper off, rider triggers are likely and still occurring. Backcountry travel requires local knowledge, extensive experience and training. The obvious clues that show snowpack instability may not be there. You need to dig deep, do your detective work and make good decisions. With forecast snow, wind and rising freezing levels, you can expect to see the danger ratings elevate over the weekend.
Snowpack Summary
New windslabs are developing from new snow and strong westerly winds. There are reports that down 30-40 cm is a preserved stellar interface that is providing easy, sudden planar test results, and a rutschblock score of 2 (whole block failing). The mid February interface (crusts at lower elevations, and buried surface hoar in sheltered locations) is down approximately 60 cm below the surface. Below this the lower snowpack is well bonded and strong.
Problems
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.
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.