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Avalanche Forecast

Archived

Dec 17th, 2023–Dec 18th, 2023

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Cariboos, North Columbia, Blue River, Clearwater, Premier, Quesnel, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, Central Selkirk.

Start on small slopes and watch for signs of instability, overhead hazard and a buried layer of weak surface hoar.

Riders continue to be surprised by large avalanches sliding on this layer.

Confidence

Moderate

Avalanche Summary

Several touchy, small to large (up to size 2.5) rider-triggered persistent slab avalanches were reported northwest of Golden in the last week. This indicates that the early December surface hoar layer is still easy to trigger in certain terrain. They have mostly occurred in treeline and alpine terrain, but have been reported as low as 1950 m. This Mountain Information Network (MIN) post from neighboring Glacier National Park is the most recent occurence.

Snowpack Summary

10 to 20 cm of recent snow and moderate southwest wind has formed windslabs over old wind-affected snow, sun crusts on steep south aspects, and surface hoar in sheltered areas. 25 to 40 cm below the snow surface, a rain crust has been observed up to 2100 m around Revelstoke, 1500 m around Mica Creek, and not at all around Blue River.

A concerning layer of surface hoar is now buried 50-80 cm deep. This layer has recently been reactive to human triggering above 1900 m.

The lower snowpack is generally faceted, but shows signs of strengthening and rounding. A hard crust may be found near the ground.

Average treeline snowpack depths are around 80-120 cm. Snowpack tapers rapidly as you move lower in elevation.

Weather Summary

Sunday Night

Mostly cloudy. Trace of snow expected. Light southwest ridgetop wind. Treeline high around -4°C. Possible temperature inversion.

Monday

Mostly cloudy. Possible trace of snow expected, up to 5 cm in the north end of the forecast area. Light south ridgetop wind. Treeline temperature around -3 °C. Possible alpine temperature inversion.

Tuesday

Cloudy. 2-5 cm of snow expected. Light south or southeast ridgetop wind. Treeline temperature around -2 °C. Possible alpine temperature inversion.

Wednesday

Cloudy. 5-10 cm of snow expected. Light to moderate southwest ridgetop wind. Treeline temperature around -3 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make observations and assess conditions continually as you travel.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Carefully evaluate steep lines for wind slabs.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.