Avalanche forecast

North Columbia

Mar 17 – 18, 2022Avalanche Canada
View on map
Archived · expired 5 years ago

Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Highlights

Buried weak layers continue to be reactive to triggers. Stick to conservative terrain with minimal overhead hazard and watch for signs of instability like whumpfing, natural avalanches and cracking.

Find more information on this tricky layer here.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Expect freshly wind loaded features to be reactive to human triggers as southwest winds continue. 

    Be aware that small avalanches in motion may step down to deeper layers. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1.5–3

    New snow continues to add load to a weak layer buried 30-60 cm deep. Large avalanches have been triggered on these layers within the last 3 days.

    • On south facing slopes a layer of crust and facets can be found at all elevations. 
    • On other aspects, a large layer of surface hoar is most concerning on sheltered treeline slopes. 

    Most reactivity has been seen around Malakwa (Queest/Gorge area), Highway 23 North (Downie Creek and Goldstream FSR areas) and terrain surrounding Valemount and Blue River. 

    More information can be found here in the new forecaster blog. 

Confidence

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

THURSDAY NIGHT: Up to 10 cm of snowfall possible overnight. Moderate southwesterly winds. Freezing levels drop to 500 m. 

FRIDAY: Scattered flurries continue with mostly cloudy skies. Moderate southwesterly winds. Freezing levels rise to 1500 m. Alpine high of -1.

SATURDAY: Scattered flurries with mostly cloudy skies, 5 cm possible over the day. Moderate southwesterly winds. Freezing levels rise to 1700 m. Alpine high of +1.

SUNDAY: 5-10 cm possible overnight. A mix of sun and cloud with moderate northwesterly winds. Light westerly winds. Freezing levels around 1300 m, alpine high of -3. 

Avalanche Summary

Reports from Wednesday continue to indicate a reactive and unstable snowpack. 

  • Several natural slab avalanches up to size 2 were reported within the most recent 25 cm of storm snow.
  • Numerous human triggered avalanches were also reported, with several remotely triggered avalanches occurring on the buried weak layers of surface hoar, facets and crust. Activity mainly occurred on south and east facing slopes around treeline, producing avalanches up to size 2.5.

On Tuesday, numerous natural and human triggered avalanches were reported on these same layers.

Snowpack Summary

40-60 cm of settling storm snow is being redistributed into wind loaded features at higher elevations. At lower elevations moist snow or a melt-freeze crust likely exists from recent rain and warm temperatures.

This new snow is sitting on various surfaces, including sun crusts on southerly slopes, facetted snow, and isolated pockets of surface hoar. The new snow is bonding poorly to this old surface, producing large avalanches within the last 3 days. 

The late February persistent weak layer combination of crust, facets and surface hoar is down 30-40 cm. Reports suggest this layer is not a problem in most areas. Two persistent weak layers from mid-February and late January are buried 50-120cm deep. No recent avalanches have been reported on these layers.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Regions covered