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Avalanche Forecast

Archived

Dec 17th, 2023–Dec 18th, 2023

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

Regions

Glacier.

A weak layer at the ideal depth for human triggering continues to produce large avalanches.

The safest way to manage this problem is through conservative terrain use.

Confidence

Moderate

Avalanche Summary

Riders continue to trigger large avalanches on the Dec 1st surface hoar. On Sunday a group triggered a size 2 in rocky terrain on Balu Peak and two other recent close calls occurred near by. One on Ursus Minor, one near the 7 steps in the Asulkan valley. East of the park on Thursday an experienced group triggered a size 2 avalanche on the same layer with one skier partially buried.

On Saturday, a few large storm slab avalanches came from the steep terrain of the Eastern Hwy Corridor.

Snowpack Summary

Up to 20cm of recent snow buries wind effect, spotty surface hoar, and a thin sun crust in steep terrain.

A rain crust down 40-50cm is present up to 2100m.

A weak layer (Dec 1st surface hoar) buried 50-90cm deep, continues to produce 'sudden' results in snowpack tests and has been the failure plane for several human triggered avalanches recently.

The base of our unseasonably thin snowpack is unsupportive and facetted in shallow areas at upper elevations.

Weather Summary

Steady weather for the next few days. Other than a rise in freezing levels (fzl) on Monday, light to moderate winds and light precipitation amounts set the trend.

Mon: Cloudy w/ flurries - trace of new snow, high 0°C, moderate S winds, fzl 1900m.

Tues: Cloudy, isolated flurries - trace of new snow, low -3 °C, light SW winds, fzl 1700m.

Wed: Cloudy, flurries up to 6cm, low -3 °C, moderate SW winds, fzl 1700m.

Terrain and Travel Advice

  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

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.

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.