Northwest Coastal

Stick to conservative terrain during stormy weather and watch for signs of instability. New snow and winds will add load to existing weak layers, making human triggered avalanches likely. Caution in known hot spots near the Nass Valley / Sterling and Beaupre riding areas.  

Tuesday night: Scattered flurries, trace-5 cm new snow, alpine low temperatures - 3C, freezing levels 300m winds moderate south. 

Wednesday: Snow flurries, 5-20 cm new snow, alpine high temperatures -3C, freezing levels 500m & ridgetop winds moderate from variable directions. Southern regions are forecast to receive higher snowfall amounts.

Thursday: Mainly cloudy with scattered flurries, trace-5 cm new snow, alpine high temperatures -4C, freezing levels 300m & ridgetop winds light to moderate west. 

Friday: Snow flurries, 10-20 cm new snow, alpine high temperatures -3C, freezing levels 700m & ridgetop winds moderate to strong southeast. 

Fresh wind slabs continue to produce avalanches (size 1-2) when tested with explosive and by skis. There was also a large natural avalanche (size 2.5) reported on the 27th east of Terrace. Accidentally triggered avalanches illustrate continued reactivity in the riding areas north of Terrace. We are glad everyone appears to be ok. 

On the 28th, there was an accidentally triggered large avalanche (size 2) reported in the Sterling area. On the 27th an accidentally triggered very large (size 3) avalanche was reported from the Beaupre riding area with a crown of 1-1.5 m. While neither reports a failure plane, buried surface hoar is likely since touchy conditions were reported in this region since the 21st on surface hoar (see this MIN & this MIN).  

At the height of the Christmas Eve storm and for the following days, widespread large and very large avalanches were reported. One avalanche among these that stands out was a very large (size 3.5) wind slab was reported to have released naturally on a southwest aspect and technicians suspect this deep wind slab failed on surface hoar following east winds.  

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!

Forecast 10-25 cm snow by the end of the day Wednesday will arrive with moderate to strong south/southwest winds which will build fresh wind slabs in exposed treeline and above. This new snow will bury recently formed surface hoar as well as add load to existing weak layers buried deeper in the snowpack. Buried older wind slabs(100-150 cm) may remain reactive, especially where they sit on top of surface hoar.

Significant variability exists with buried weak layers. Beneath recent 10-25 cm is a surface hoar layer that has been reported in the Shames areas and appears quite widespread treeline and below. Last week's 40-60 cm of snow may sit atop a crust or surface hoar layer as was reported in Shames. A zone of reactivity has been noted in riding areas along highway 113 north of Terrace, which may be due to a deeper surface soar layer in this zone coupled with recent wind slabs. A crust that was buried in early December is now down 90-200 cm plus and has facets and potentially the above mentioned surface hoar in sheltered areas. 

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.

• Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
• Recent wind has varied in direction so watch for wind slabs on all aspects.
• Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.