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Avalanche Forecast

Archived

Dec 13th, 2024–Dec 14th, 2024

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

Regions

Glacier.

Windy storm ahead this weekend!

Expect new wind slabs to form and be sensitive to rider triggering.

Confidence

Moderate

Avalanche Summary

Natural avalanche activity has mostly tapered off since last weekend's storm. A few size 1 loose moist avalanches observed yesterday from steep solar aspects.

Artillery control produced excellent results on Tupper and Macdonald the night of the 7th, with most shots producing sz 2 to sz 3 avalanches from steep start zones, running out onto valley bottom fans. Debris moved fast, likely picking up speed and mass on the buried surface hoar.

Snowpack Summary

50-70cm of storm snow sits on a sun crust on steep solar aspects. In sheltered locations, this new snow sits atop surface hoar. Strong SW winds at the end of the storm created surface slab conditions on exposed Treeline and Alpine slopes.

There is a dense, well-settled mid-pack without any significant weak layers.

The Nov 9 crust is down 1-1.5m. The base of the snowpack is comprised of several dense, melt-freeze rain crusts formed in October.

Weather Summary

A windy weekend storm will bring light to moderate snow through to Monday.

Tonight: Flurries, trace of snow. Alpine Low -6. Moderate South wind, Freezing level(FLZ): 1000m

Sat: Flurries, 10cm. Alpine high -5 °C. Moderate gusting to Strong SW winds. FLZ: 1400m

Sun: Mix of sun and clouds w/flurries, 6cm. Alpine high -7. Moderate to strong SW winds. FLZ: 1100 m

Mon: Flurries, 7cm. Alpine high -10. Light SW wind. FZL 900m

Terrain and Travel Advice

  • Be careful as you transition into wind-affected terrain.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Carefully manage your exposure to overhead hazards.

Problems

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.

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.