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Avalanche Forecast

Archived

Mar 31st, 2022–Apr 1st, 2022

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

South Columbia.

Wind slabs may be reactive to human triggering at upper elevations, especially where they sit above a crust.

Conditions can change quickly with rain or strong solar input destabilizing the snowpack. Be ready to adjust your plans and scale back your exposure to avalanche terrain.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Friday: Mostly overcast skies with 5-10 cm of new snow. Ridgetop wind will be moderate from the West. Freezing levels will likely rise to 1500 m during the day and fall to the valley bottom overnight.

Saturday/ Sunday: Mostly cloudy with convective flurries possibly bringing 5-20 cm. Ridgetop wind is moderate from the southwest and freezing levels will remain near 1500 m.

Avalanche Summary

On Wednesday, the recent storm snow was easily reactive to skier triggering, especially where it sits above a crust. Reports showed numerous dry loose and wind/storm slab avalanches size 1-2.

On Tuesday in the north of the region, several size 1-2 natural wind slabs were observed in the alpine. Throughout the region, a widespread wet loose/wet slab and deep persistent slab avalanche cycle occurred at all elevations up to size 3. The most reactivity was noted on solar aspects.  

Snowpack Summary

Up to 20 cm of new snow overlies 10-20 cm of denser snow above 2000 m. A crust can be found below the new snow on all aspects below 2500 m. Below the crust, the top 10-30 cm of the snowpack is moist. Moderate West wind combined with the recent snow has formed reactive wind slab on lee terrain features in the alpine and at treeline. 

At lower elevations (below treeline) a thick and robust melt-freeze crust exists making the snowpack strong. If the crust breaks down and softens to moist and/or wet snow, the snowpack becomes weak. 

Several older crust layers exist in the upper snowpack and were buried in mid-March and near the end of March. A deeper one formed in December and exists approximately a metre off the ground. Reports have recently indicated that large slab avalanches have failed on some of these interfaces within the past few days following a rain and warming event. The most reactive slopes were south-facing. These layers may be dormant now until the next warm-up or increased load from wind, snow and/or rain. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.
  • As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.

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.