Potentially deep wind slabs can be found in exposed terrain, especially immediately lee of ridge crest. Caution is needed in the trees right now too, the most recent storm snow is resting on a surface hoar layer that seems to be fairly widespread in the north of the region.
Recent winds have varied in direction so wind slabs can be found on a variety of aspects. Be mindful that wind slab avalanches can serve as triggers for deeper weak layers, resulting in large and destructive avalanches.
In wind sheltered terrain it's been widely reported that storm snow is resting on a thin layer of surface hoar in the northern portion of the region. Don't let your gaurd down in the trees right now.
We’re moving into a dryer period that is expected to be with us for the foreseeable future. Freezing levels look very reasonable for the middle of February and there is a lot of sun in the forecast Sunday through Wednesday.
SATURDAY NIGHT: Freezing level around 1400 m, moderate west/northwest wind, trace of snow possible.
SUNDAY: Broken cloud cover, freezing level around 1000 m, light to moderate west/southwest wind, trace of snow possible.
MONDAY: Broken cloud cover in the morning clearing by sunset, freezing level around 900 m, light northwest wind, no significant precipitation expected.
TUESDAY: Clear skies, freezing level rising to about 1200 m, light variable wind, no significant precipitation expected.
On Friday the upper 20 cm of storm snow was sensitive to human triggering on steep rollover features. There was a report from late in the day Saturday of a small skier triggered avalanche on Mt. Thar, details in this MIN.
Natural wind slab avalanches up to size 2 were observed on steep, north to east facing alpine terrain on Tuesday.
On Wednesday, two cases of wind slab avalanches stepping down to deep persistent layers were reported: one was skier triggered from a thin spot in an aggressive north facing alpine feature (link to MIN report), the other a natural size 2.5 on a convex southeast aspect in an open area around treeline.
On February 9th In the neighboring Sea to Sky region, a very large (size 3.5) avalanche occurred on near Whistler on a steep north face at 2400 m. These avalanches are suspected to have failed on a layer of facets on a crust from late November. These events demonstrate the ongoing need for caution in aggressive terrain, particularly in areas where deep instabilities remain.
Up to 20 cm of storm snow has fallen over the last few says. In the north of the region this snow rests on surface hoar in sheltered locations. On solar aspects surface hoar has been observed on a sun crust which is a problematic setup. In wind exposed terrain it has been formed into fresh sensitive wind slabs. We haven't hear of any surface hoar in the South of the region yet.
Previous to this storm wind redistributed recent snow producing wind slabs in the alpine and upper treeline vegetation bands. In more sheltered terrain up to 30 cm of less dense snow can be found. Solar aspects have a thin sun crust under the storm snow.
There are a couple of crusts deeper in the snowpack, down 30-40 cm and 60-110. The mid-pack is considered to be well settled and strong.
In the north part of the region (ie. Goldbridge/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. Sporadic avalanche activity on these layers keep them on our radar. In the south of the region, including the Coquihalla and Manning areas, we currently have no concerns about deeply buried weak layers.
