Avalanche Forecast

Moderate - We have a good understanding of the snowpack structure and confidence in the weather forecast Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

Wednesday Night: Mostly clear. No new snow expected. Winds decrease to light from the southwest, moderate northwest at higher elevations. Freezing levels at valley bottom. Possible temperature inversion keeps Alpine lows around -5 C.

Thursday: Mostly sunny. No new snow expected. Light southwest wind trending to moderate northwest at higher elevations. Freezing levels at valley bottom overnight, and rising to 600 m through the day. Possible temperature inversion brings alpine highs to around -3 C.

Friday: Partly cloudy. No new snow expected. Light southwest wind trending to strong west at higher elevations. Freezing levels at valley bottom overnight, and rising to 600 m through the day. 

Saturday: Mostly sunny. No new snow expected. Light southwest wind trending to strong west at higher elevations. Freezing levels at valley bottom overnight, and rising to 600 m through the day. 

A few thin crust and/or surface hoar layers in the upper snowpack have been producing isolated sudden results in snowpack tests. While this is not a cause for widespread concern, it is worth gathering some extra snowpack information before committing to a feature. 

No new avalanches reported by 4 pm on Wednesday.

On Sunday, a large natural avalanche was reported in the backcountry near Whitewater. After talking to some professionals in the area, it sounds like it occurred late last week during the storm. There is a great picture in this Mountain Information Network post. It was a wide propagation, and it looks like it started mid-slope on a sparsely treed ridge. There was a similar avalanche on the same feature in a previous storm, so this may be a new slide on a reloaded bed surface.

There are reports of a surface crust on steep solar aspects from the recent warm temperatures and sun, 1-10 cm thick. Surface hoar growth is widespread in terrain that hasn't seen recent wind, mostly 5-10 mm, and up to 25 mm. The thickest crusts and largest surface hoar have been reported around Whitewater ski resort. Thinner surface crusts may be breaking down with overnight cooling and surface hoar formation. 

A series of recent surface hoar layers and melt-freeze crusts can be found in the top 50 cm of the snowpack, up to 2400 m. The crusts are thicker on southerly aspects (up to 6 cm). These layers have not been resulting in recent avalanches and have not produced concerning results in snowpack tests yet. 

A strong, well-consolidated mid-pack exists below this and above the early December crust/facet interface. 

The early December crust/facet layer has been responsible for sporadic but very large, persistent slab avalanches over the past month. The crust is now buried 120-200 cm deep except in thin, wind-affected areas near ridgetops. Daytime warming, sun, cornice fall, and smaller avalanches could all play a role in triggering low probability, high consequence deep persistent slab avalanches. 

• Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
• Carefully evaluate bigger terrain features on an individual basis before committing to them.
• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
• Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.