Wind has redistributed recent storm snow building more reactive deposits around ridges and convex rolls. A spotty layer of surface hoar has been reported at lower elevations under the recent snow, dig down and investigate the bond of new and old snow before committing to terrain.
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 recent storm snow is resting on a thin layer of surface hoar in the northern portion of the region. Don't let your guard down in the trees right now.
We’re moving into a dryer period that is expected to be with us for the foreseeable future. Temperatures look reasonable for the middle of February and there is a lot of sun in the forecast through Wednesday.
SUNDAY NIGHT: Mostly clear. Alpine low temperature -10 C. Northwest wind 15-30 km/hr. Freezing level valley bottom.
MONDAY: Mix of sun and cloud. Alpine high temperature -8 C. Northwest wind 10-25 km/hr. Freezing level 800 m.
TUESDAY: Sunny. Alpine high temperature -4 C. Southwest wind 10-15 km/hr. Freezing level 1300 m.
WEDNESDAY: Sunny with clouds. Alpine high temperature -2 C. Southwest wind 15-30 km/hr. Freezing level 1500 m.
On Friday the upper 20 cm of storm snow was sensitive to human triggering on steep rollover features. The trend continued Saturday with sluffing in steep terrain and reactive pockets of wind slab. This MIN report provides details of a small skier triggered avalanche on Mt. Thar. Wind slab avalanches were reported on steep north to east facing terrain earlier in the week, new snow may be covering older wind slabs.
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.
10-20 cm recent storm snow is wind affected in alpine and open treeline areas forming fresh wind slabs. In sheltered locations, the new snow covered a thin layer of surface hoar (in the north of the region). On solar aspects surface hoar has been observed on a sun crust which is a problematic setup. We haven't heard 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.
