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Avalanche Forecast

Archived

Apr 7th, 2022–Apr 8th, 2022

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

South Columbia.

The weather pattern right now is dynamic and fast-changing, and we're unsure about how the snowpack will react. During times of uncertainty, lean on a conservative approach to terrain, a cautious mindset and continually make observations as you travel. 

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

Thursday Night: WARM. Freezing levels stationary near 3000 m and forecast to drop to 2000 m by mid- morning Friday. Ridgetop winds light from the southwest.

Friday: Cloudy with possible sunny breaks. Up to 10 cm of new snow at upper elevations and light ridgetop wind from the southwest. Freezing levels dropping to 2000 m by 10 am.

Saturday: Cloudy with sunny periods. New snow 5-10 cm and freezing levels 1200 m. Alpine temperatures near -8 C and ridgetop winds light from the northwest. 

Sunday: Mix of sun and cloud. Chance of flurries up to 5 cm. Freezing level near 1200 m and alpine temperatures -8 C. Ridgetop winds light from the West.

Avalanche Summary

On Wednesday, reports showed a wide range of avalanche activity. A natural storm/ wind slab and wet loose cycle was seen up to size 2.5. An older (occurred on April 5th) persistent slab was reported size 2.5, failed on the late March crust on a southwest aspect near 2200 m. Several human triggered size 2 slab avalanches were also reported. 

Monday and Tuesday saw evidence of a widespread natural avalanche cycle up to size 3 but the average storm/ wind slabs were reported to size 2 and failed in the recent storm snow. Some larger avalanches may have failed on the end of March melt-freeze crust. Most notable was a natural size 3.5 storm slab that started at 2600 m and ran to the valley bottom. 

Snowpack Summary

Moist snow surfaces exists up to 2000 m on most aspects and to ridgetop on solar slopes. This will likely exist at higher elevations by Friday.

15 to 30 cm of storm snow has buried multiple crusts in the upper snowpack. Moderate southwest wind has redistributed some of the new storm snow in exposed high elevation terrain forming wind slabs and large cornices.

The new snow brings 60-80 cm above a crust from late March. This crust is present on all aspects up to an elevation of 2600 m and has shown avalanche activity over the past few days.

The early-December rain crust is approximately a metre off the ground. Large slab avalanches failed on this interface last week following a rain and warming event. This layer may be active with no overnight refreeze and warm weather. 

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of a buried crust.
  • Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
  • In times of uncertainty conservative terrain choices are our best defense.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.