Avalanche Forecast
Issued: Feb 17th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
dsaly,
Avalanche Canada
Sun and warm temperatures help the snowpack settle and bond. Keep an eye on sunny slopes warming through the day, move to more shaded terrain and avoid overhead hazards if the surface snow becomes moist or wet.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Partly cloudy. Alpine low temperature 12 C. Northwest wind 10-20 km/hr. Freezing level valley bottom.
TUESDAY: Sunny. Alpine high temperature -4 C. North wind 10-20 km/hr. Freezing level 1000 m.
WEDNESDAY: Sunny. Alpine high temperature -1 C. Southwest wind 15-25 km/hr. Freezing level 1300 m.
THURSDAY: Mostly sunny. Alpine high temperature -2 C. Southwest wind 20-30 km/hr. Freezing level 1300 m.
Avalanche Summary
On Friday the upper 20 cm of storm snow was sensitive to human triggering on steep rollover features. Slab reactivity continued Saturday with sluffing in steep terrain and pockets of wind slab reactive to skiers, this MIN report provides details of a small skier triggered avalanche on Mt. Thar. On Sunday skiers reported a touchy wind slab, triggering several size 1-2 wind slab avalanches, many occurring on north to east aspects or wind loaded terrain.
Last 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 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 deep persistent avalanche events demonstrate the ongoing need for caution in aggressive terrain, particularly in areas where deep instabilities remain.
Snowpack Summary
West-southwesterly winds have redistributed 10-25 cm recent storm snow, wind slabs have formed in open treeline areas into the alpine. Initially the new snow did not bond well to the old surface - sloughing and loose, dry avalanches were easily triggered in sloped terrain. The new snow covered wind affected surfaces at upper treeline and above and covered up to 30 cm older snow in more sheltered areas. Solar aspects have a thin sun crust under the storm snow. A spotty layer of surface hoar has been reported in sheltered terrain under the recent snow in the north of the region. We haven't heard of any surface hoar in the South of the region yet.
There are a couple of crusts deeper in the snowpack, down 30-40 cm and 60-110 and remain unreactive. 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.
Terrain and Travel
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
Problems
Wind Slabs
Wind slabs can be found on a variety of aspects, the most reactive pockets may around lurk steep alpine and ridgetop lee features. Be mindful that wind slab avalanches can serve as triggers for deeper weak layers, resulting in large and destructive avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 18th, 2020 5:00PM
