Avalanche Forecast

Issued: Jan 18th, 2020 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada mconlan, Avalanche Canada

New slabs are expected to grow and become more sensitive as the snow accumulates, the wind continues to blow, and the air temperature increases.

Summary

Confidence

High -

Weather Forecast

SATURDAY NIGHT: Cloudy with snowfall, accumulation 2 to 5 cm, moderate to strong southwest wind, alpine temperature -7 C, freezing level below valley bottom.

SUNDAY: Cloudy with snowfall, accumulation 5 to 15 cm, moderate to strong southwest wind, alpine temperature -5 C, freezing level rising to 1000 m.

MONDAY: Mostly cloudy with isolated flurries, accumulation 1 to 3 cm, moderate to strong southwest wind, alpine temperature -3 C, freezing level 1000 m.

TUESDAY: Cloudy with snowfall, accumulation 5 cm, light south wind, alpine temperature -5 C, freezing level 600 m.

Avalanche Summary

Many small to large (size 1 to 1.5) wind slabs were triggered naturally and by humans on Thursday and Friday. They were most often triggered on northwest to northeast aspects but some occurred on south aspects as well. The slab depth ranged from 10 to 100 cm deep and they occurred at treeline and alpine elevations. A few large (size 2 to 2.5) wind slabs were also triggered, suggesting that the wind slabs have the capability of being deep and propagating far.

Persistent slab activity has tapered off in the past week, although there have been occasional reports of large (size 3) explosive-triggered avalanches in alpine terrain (one or two a week).

Snowpack Summary

Strong southwest wind and around 10 to 20 cm of new snow will form fresh storm slabs, with the most reactive slabs being in lee terrain features at higher elevations. The slabs may develop quickly due to relatively warm air temperature.

A thin melt-freeze crust can be found 50-100 cm below the surface in many areas, and beneath that a layer of surface hoar may still be found, which is roughly 80-120 cm deep in the Selkirks and 120-160 cm deep in the Monashees. A facet/crust layer from late November may be found near the bottom of the snowpack. These layers appear to be unreactive at the moment, but could reappear as problems in the future.

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Be aware of the potential for wide propagation.

Problems

Storm Slabs

An icon showing Storm Slabs

Around 10 to 20 cm of snowfall along with strong southwest wind and a warming trend will all work together to form new slabs. They will be deepest and potentially touchiest in lee terrain features in exposed terrain, particularly near ridges.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 19th, 2020 5:00PM

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