Avalanche Forecast

Moderate - Uncertainty is due to the limited number of field observations. Confidence is due to a stable weather pattern with little change expected.

Continued cloudy conditions with clear periods and cool temperatures tonight and Monday before the next weather maker arrives Tuesday afternoon bringing moderate snowfall and increased winds.   

 

Sunday night: Mainly cloudy with clear periods. Alpine low temperatures near -4C and freezing levels valley bottom. Ridgetop wind light to moderate northwest. 

Monday: A mix of sun and clouds. Alpine high temperatures near - 4C and freezing levels valley bottom. Ridgetop winds increasing to moderate northwest. Mild alpine temperature inversion with cool cloudy valleys and clear skies above. 

Tuesday: Mainly cloudy with snow flurries in the afternoon, trace to 10cm new snow late in the day, alpine high temperatures near -4C and freezing levels valley bottom. Ridgetop wind increases moderate to strong from the south/southwest. 

Wednesday: Mainly cloudy with snow flurries, trace new snow. Alpine high temperatures near -2C and freezing levels valley bottom. Ridgetop wind light from the southwest/southeast gusting moderate. 

Cooler temperatures and a reduction in winds and new snow inputs have allowed the snowpack to begin to recover from the recent Christmas eve storm. At the height of the storm and for the following days, numerous large avalanches were reported. Reverse loaded wind-slabs from east winds created reactive windslabs on west and south west aspects which produced large (size 2) and very large (up to size 3.5) avalanches when tested with explosives. This MIN from the Shames back-country reports a couple small (size 1) avalanches.  

This natural cycle has tapered, but human triggered avalanches remain likely, especially where wind has stiffened recent snow into windslabs or where storm slab sits atop weak layers. Reactive large windslab avalanches (size 2) were reported as recently as yesterday. Some of these may have failed on the Surface hoar layer down 40-80cm. Step-down avalanches are a significant possibility where a small wind slab or cornice fall may trigger a large and destructive avalanche.

Please consider sharing your observations with the Mountain Information Network; even just a photo of your day helps. Thank you to those that have already submitted this winter!

Snow surfaces are variably wind affected in the alpine, exposed treeline and open areas below treeline. Recent 30-50cm of snow has been redistributed in many of these windy areas. Western aspects were heavily wind loaded from east winds during and since the recent Christmas Eve storm. Look for signs of wind effect for clues to how the wind has impact the snow: scoured surfaces, sastrougi, reverse wind loading, cross loaded gullies and deep wind slabs (100-150cm deep) in lee features. As winds shift back to a more typical westerly pattern be aware of buried windslabs, 

In sheltered locations recent snow is settling rapidly with mild temperatures. New snow may sit atop a crust or surface hoar layer that formed before this recent storm that is buried 40-80 cm. A buried surface hoar has been evident in the Nass Valley riding area and more recently in Shames back-country, as reported in these MIN's. These are likely two different surface hoar layers - but are buried at similar depths.

A crust that was buried in early December is now down 90-120cm plus and has been reported to be gaining strength, but we remain wary of it's slick sliding surface should an avalanche propagate on this layer. Around this crust are facets and potentially surface hoar in sheltered areas. Storm slabs may step-down to this layer.

The early-November crust is buried around 170-200 cm at treeline and deeper in the alpine. This crust may have weak and sugary facets above it in parts of the region. This layer is currently dormant but remains on our radar.

• Recent wind has varied in direction so watch for wind slabs on all aspects.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.