With a bit more wind and snow and slightly milder temperatures we could reach "the tipping point" very soon. Check out the latest post in the Forecaster's Blog for more information.
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Tonight and Tuesday: Moderate snowfall - 5-10cm tonight and an additional 10-15cm tomorrow. Winds increase to moderate-strong from the west. The freezing level (FL) is near valley bottom tonight rising to 1200m on Tuesday. Wednesday: Continued light to moderate snowfall - 5-10cm. FL dropping to 800-1000m. Winds should be moderate-strong from the west-northwest. Thursday: Cooler and drier under a brief ridge of high pressure. FL dropping to around 500m.
Avalanche Summary
There are several reports of natural and skier triggered avalanches up to Size 1.5. These avalanches occurred in wind affected terrain in the alpine, or on steep convex shaped features below treeline. The size and likelihood of avalanches will increase as the new snow settles into a more cohesive slab.
Snowpack Summary
Wind slabs continue to grow in exposed terrain in response to moderate W-SW winds. 15-40cm of low density snow overlies the Feb. 9 weakness, which includes surface hoar and/or a crust. This surface hoar layer may be widespread in some areas, while others have reported it being confined to shady aspects at treeline and in the alpine. A melt-freeze crust has developed on solar aspects at all elevations, and on all aspects below about 1600 metres. The mid-pack is generally well settled. There is some concern that large loads like cornices may trigger the Jan. 20th facet layer. Some shallow snowpack areas may continue to have a weak layer of basal facets near the ground.
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.