Regions
South Coast Inland.
More snow forecasted in the south of the region Saturday night will keep the hazard at Considerable. Observe for the bond of the snow with the underlying crust before committing into avalanche terrain. Be particularly cautious if the sun comes out.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
SUNDAY: 10 to 20 cm snowfall in the south of the region early-morning, otherwise a mix of sun and cloud with late-afternoon snowfall, light northeast winds, alpine temperature -4 C, freezing level 1500 m.MONDAY: Cloudy with snowfall, accumulation 15 to 20 cm, light west winds, alpine temperature -5 C, freezing level 1400 m.TUESDAY: Mostly cloudy, light west winds, alpine temperature -5 C, freezing level 1500 m.
Avalanche Summary
Numerous small wind slab avalanches were triggered by skiers on Friday, 20 to 35 cm deep and on northerly aspects in alpine terrain. These were running within the recent storm snow on the melt-freeze crust. They were reported as easy to initiate, indicating that the bond between the new snow and the crust is poor.
Snowpack Summary
Around 30 to 50 cm of snow has fallen in the region between Thursday and Saturday. This snow overlies a thick and hard melt-freeze crust. On ridges, cornices are reported to be large and fragile. At low elevations below treeline, recent rain has created moist or wet snow conditions.A weak layer consisting of surface hoar, facets, and/or a melt-freeze crust from late March is now buried about 50 to 100 cm. This layer is spotty in its distribution. It is mostly likely to be problematic on west, north, and east aspects between 1900 m and 2250 m.The mid and lower snowpack are well-settled and strong.
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.
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.