Avalanche forecast

North Columbia

Dec 31, 2017Avalanche Canada
View on map
Archived · expired 9 years ago

Avalanche danger

Mon
Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
Open full map

Highlights

The region has seen higher snowfall amounts than weather forecasts have indicated. A cautious approach is recommended in the coming days as temperatures gradually rise and the recent storm snow settles and consolidates more rapidly.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    A weak layer of surface hoar buried 50-80 cm deep has potential to be reactive in areas where the overlying snow has settled into a cohesive slab.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    30 to 50cm of low density new snow has accumulated in the region the past 3 days. Where accumulations are higher expect the new snow to sluff and gather mass in steep terrain. Westerly winds have created windslabs in alpine and tree line lees.

Confidence

Moderate - Freezing levels are uncertain on Tuesday

Weather Forecast

SUNDAY: Mix of sun and cloud / Light west wind / Alpine temperature -13 MONDAY: Mix of sun and cloud / Light to moderate west wind / Alpine temperature -5 TUESDAY: Mix of sun and cloud / Moderate northwest wind / Alpine temperature -2, possible temperature inversion

Avalanche Summary

Recent reports show natural several storm snow avalanches to size 2 at tree line and in the alpine on all aspects. There have been a few reports of remotely (from a distance) triggered persistent slab avalanches to size 2 on northerly aspects between 1700 and 2000m. Consider the potential to trigger persistent slabs as the recent storm snow settles more rapidly on top of the Mid-December persistent weak layer with gradually warming temperatures in the coming days.

Snowpack Summary

30-50cm of low density new snow has buried a recently formed layer of weak feathery surface hoar and/or sugary facets. A layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is now down approximately 50-70cm.The bond at this old snow interface is of critical importance in areas where the overlying snow has consolidated into a slab. The most concerning areas are those that saw pronounced surface hoar development before mid-December, such as sheltered areas at and below treeline, sheltered northerly aspects in the alpine, or anywhere the surface hoar formed on top of a sun crust. Recent snowpack tests show wide ranging reactivity on this weak layer but suggest that it may be most reactive on northerly aspects. A rain crust that formed in late November is now buried 80-120cm deep. A report from last week in the southwest end of this region suggests it may be reactive in steep, variably loaded terrain features in the alpine.

Regions covered