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Avalanche Forecast

Archived

Mar 1st, 2022–Mar 2nd, 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.

Regions

Kootenay Boundary.

Though natural avalanche activity will taper off, conservative decision making is essential to let the snowpack adjust to the recent 65+ mm of load that the Kootenay-Boundary has received. 

Seek out low angle, well supported terrain away from overhead hazard.

Confidence

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

Weather Forecast

Tuesday night: light snow possible 0-5cm, moderate to strong southwest wind, freezing levels likely remain elevated hovering around 1700-1900 m, treeline highs around +2.

Wednesday: Light snowfall trace amounts possible, light to moderate southwest wind, freezing levels around 1700 m, treeline highs +2.

Wednesday night into Thursday: Light flurries possible 0-5 cm, wind light and variable, freezing levels between 1500-1700 m during the day.

Friday: Clearing, good overnight recovery, light to moderate northeast wind, treeline highs around +2.

Avalanche Summary

On Tuesday explosives control triggered large slab avalanches in the size 2-3 range. Although visibility has been poor a couple of natural storm slabs in the size 2.5 range have also been spotted.

On Monday there were various reports of natural and rider-triggered avalanches in the size 1-2 range, some with surprising propagation.

Snowpack Summary

The storm started cool and then it got warm! Some places in the Kootenay boundary have received over 60 mm of water from this system. That has translated to about 20-40 cm of heavy, upside-down type snow forming reactive slabs on all aspects. Rain runnels have been reported up to about 1800 m. The new snow sit on top of sun crusts on south-facing terrain, freezing rain crusts, old wind-pressed snow, and cold weak snow crystals on shaded aspects. Moderate to strong southwest winds have likely contributed to cornice growth and some wind loading as well.

Weak layers from mid-February and late January made up of crusts and/or surface hoar crystals can be found around 60-70 cm deep. There are not a lot of recent avalanches on these layers, but they are still on the radar of operators in the area.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Use small low consequence slopes to test the bond of the new snow.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.

Problems

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.

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.

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.