If more than 15 cm of snow lies on the ground Wednesday morning, consider danger to be HIGH in the Alpine and at Treeline.
Confidence
Poor - Forecast snowfall amounts are uncertain on Wednesday
Weather Forecast
Synopsis: Continued northwesterly flow will bring moderate or locally heavy pulses of precipitation to the region interspersed with some dry patches.Tuesday night: 10-15 cm low density new snow.Wednesday: Another 10-15 cm new snow through the day. Treeline temperatures should peak around -4C. Northwesterly winds gusting to 60 km/h.Thursday: Light snowfall, 2-4 cm. Temperatures rising in the afternoon to around -1C at treeline. Moderate northwesterly winds.Friday: Some clear spells and some flurries. Temperatures around -4C at treeline. Moderate northwesterly winds.
Avalanche Summary
No new avalanches reported from this region.
Snowpack Summary
Around 40-50 cm recent new snow has settled into a 20-30 cm soft slab overlying a weak layer comprising of facets at higher elevations, surface hoar on shady slopes, and a sun crust on solar aspects. The recent new snow sitting above this interface has been slowly consolidating from fresh powder into a more cohesive slab. As this process continues, the avalanche character will change from relatively harmless loose sluffs to more dangerous slab avalanches. However, note this upper weak layer has been reported to be patchy and variable in distribution. A mid-pack layer buried in early January surface hoar layer is down 70-90 cm. While this layer is still on the radar of professional observers, with most likely trigger points being on steep rolls below 1600 m, there has only been one small avalanche (size 1 at 1200 m on a north aspect) reported on this layer from the region for approximately 10 days.
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.