Avalanche forecast

South Columbia

Apr 5 – 6, 2021Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Minimize exposure to large looming cornices weakening with daytime warming and solar radiation and be cautious on sun-exposed slopes. 

Isolated pockets of wind slab may be found in immediate leeward features in the alpine. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Wind slabs will be most likely be isolated to immediate lees of ridgecrests and roll-overs in wind exposed alpine terrain.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Cornices become weak with daytime warming and solar radiation. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–1.5

    Small loose avalanches can be expected in the new snow on steep solar aspects and at elevations where air temperature is above freezing. Below treeline, loose wet avalanches are possible where snow did not refreeze overnight.

Confidence

High -

Weather Forecast

The region will start to see the effects of the next frontal system by Tuesday night. This will bring moderate snow amounts to the Northern half of the region and light amounts to the South.

Tuesday: Mix of sun and cloud. Ridgetop wind light from the southwest. Alpine temperatures near -3 and freezing levels 2000 m. 

Wednesday: Snow 10-20 cm. Ridgetop wind moderate to strong from the southwest. Alpine temperatures -4 and freezing levels 1600 m. 

Thursday: Mix of sun and cloud with a trace of new snow. Ridgetop wind light from the southwest. Alpine temperatures near -6 and freezing lvels 1600 m. 

Avalanche Summary

On Sunday several loose-dry and skier-triggered size 1.5 avalanches were reported. The reactivity mostly occurred during daytime warming from steep slopes within the new snow.  

A size 2 skier-triggered wind slab was reported in neighboring Glacier National Park on Saturday. A couple of size 2 cornice failures were reported on Friday, one triggering a thin wind slab on the slope below. 

A bit of cloud cover and a strong southwest wind is expected to keep snow surfaces cool on Tuesday. However; if the sun is shining in your local riding area, natural avalanche activity may spike.

Snowpack Summary

5-15 cm of recent snow accompanied by strong southwest wind may have formed wind slabs on leeward slopes at upper elevations. Reports indicate the snow is bonding well to underlying surfaces which include wind-affected snow in the alpine or crust on solar aspects and below 1900 m. Below this elevation and on solar aspects the new snow dusts crusty surfaces down to 1500 m. Below 1500 m, the moist snowpack is quickly diminishing.

At alpine and treeline elevations, a few layers of note are buried 50-100 cm deep including a layer of small surface hoar crystals on shady, wind-sheltered aspects and a series of crusts on solar aspects and below 1800 m. Overall the snow seems to be bonding well to these interfaces, although there have been a few isolated avalanches running on deeper crust layers in the past week.

Terrain and Travel

  • Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
  • Use ridges or ribs to avoid areas of wind loaded snow.
  • Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches

Regions covered