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Avalanche Forecast

Archived

Mar 2nd, 2022–Mar 3rd, 2022

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

Kootenay Boundary.

Stability is gradually improving but riding quality may not be! 

There is still uncertainty surrounding reactivity of storm slabs in the alpine. Test the bond of new snow on smaller features with low consequences before committing to bigger lines. 

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.

Weather Forecast

Wednesday night: Light snowfall trace to 5 cm, light southwest wind, freezing levels around 1500 m, treeline temps around -1.

Thursday: Light flurries possible 0-5 cm, wind light and variable, freezing levels between 1500-1700 m during the day, treeline highs of +2.

Friday: Light flurries overnight trace to 5 cm easing by the morning, freezing levels dropping to valley bottom overnight. Mostly sunny during the day, light northeast wind, treeline highs around +4.

Saturday: Sunny, no new snow, light northeast wind, good overnight refreeze but temperatures will rise during the day to +2.

Avalanche Summary

On Wednesday storm slabs were still reactive (up to size 2) to small explosives. On Tuesday explosives control triggered large slab avalanches in the size 2-3 range. Although visibility was poor a widespread cycle of natural storm slabs in the size 2-2.5 range was also evident. There was a remote triggered size 1.5 avalanche reported in the east of the region as well. Some loose wet activity and pinwheeling was also reported at lower elevations.

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

Snowpack Summary

Some places in the Kootenay boundary have received over 60 mm of water from this system. That has translated to about 20-60 cm (depending on elevation) of heavy, upside-down type snow. Depending on overnight refreeze, you may find a melt-freeze crust on the surface up to 1900 m. All of this new load sits on top of sun crusts on south-facing terrain, freezing rain crusts, old wind-pressed snow, and even some feathery surface hoar crystals in some locations. 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

  • Use small low consequence slopes to test the bond of the new snow.
  • Be alert to conditions that change with elevation.
  • 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.

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.