Avalanche Forecast

Low - Uncertainty is due to how the snowpack will react to the forecast weather. Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.

A ridge of high pressure brings dry and sunny conditions for Sunday with a layer of warm air expected to reach the alpine and the potential for a temperature inversion in the valleys. 

Saturday Night: Mainly clear, light to moderate W wind, treeline temperature around -6 °C. 

Sunday: Mainly sunny with a chance of valley cloud, moderate W wind, freezing level reaching near 2000 m in the afternoon with a possible temperature inversion. 

Monday: A mix of sun and cloud, moderate to strong SW wind, freezing level around 1800 m with an inversion.

Tuesday: Mainly sunny, light to moderate W wind, freezing level reaching around 1800 m.

An early report from Saturday includes a natural cornice fall triggering a size 2 storm slab failing down 30 cm. 

On Friday, ski cutting triggered one size 1 storm slab which failed on the January 30 surface hoar as well as several shooting cracks. On Thursday, this MIN report described a snowmobile-triggered size 1 slab on an east aspect below treeline failing down 30 cm on the January 30 surface hoar.

Up to 50 cm of settling snow now overlies the January 30 interface which consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine, widespread surface hoar in sheltered areas at and below treeline, and small facets in some areas. Prior to the weekend warming, the surface storm snow was cold and mainly unconsolidated, and had not formed a slab in most places except for where it was wind loaded. With warming and sun this weekend, rapid settlement is possible and this may result in the formation of a more widespread reactive slab over the weak interface. 

Periods of strong wind over the past week has formed reactive wind slabs in exposed terrain at higher elevations and ongoing wind on Friday and Saturday, mainly from the southwest through northwest, has likely continued to develop wind slabs. 

The widespread January 18 rain crust is now around 50-70 cm deep with weak faceted snow above. This layer has not produced any recent avalanche activity but will get tested this weekend with warming and sun.

The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous large avalanches in January but is now considered dormant. See this forecaster blog on how to manage this layer as it may come into play again later this season. 

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
• The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
• Cornices become weak with daytime heating.