Avalanche Canada ldreier, Avalanche Canada

South Coast Inland Avalanche Forecast

Jan 12th, 2020 4:00PM

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

Fluffy unconsolidated snow will hide previously formed wind slabs. Deeper weak layers might still be reactive to human triggers, particularly in the north of the region.

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

SUNDAY NIGHT: Cloudy with clear periods, moderate northerly wind, alpine temperature -25 C, freezing level below valley bottom.

MONDAY: Mostly sunny, light to moderate northwest wind, alpine temperature -25 C, freezing level below valley bottom.

TUESDAY: Mix of sun and cloud with isolated flurries, moderate west wind, alpine temperature -25 C, freezing level below valley bottom.

WEDNESDAY: Mostly sunny, moderate west wind, alpine temperature -25 C, freezing level below valley bottom.

Avalanche Summary

On Saturday, the snowpack was reactive to explosive triggers. Some avalanches stepped down to a feathery surface hoar layer buried 50-60 cm deep. 

No new avalanches were reported on Friday.

On Thursday, a few explosive triggered storm slab avalanches up to size 2 were reported. One explosive triggered avalanche released on the mid November facet/crust layer.

Snowpack Summary

Unconsolidated fluffy snow of the recent storm sits on a snow surface that was wind affected by moderate to strong southerly wind. The wind formed slabs in lee terrain features in the alpine and around treeline. 

Deeper in the snowpack:

  • The previous storm snow loaded a touchy weak layer of feathery surface hoar in sheltered areas above 1800 m. Areas such as Manning, Henning, Stoyoma, Duffey, and Hurley should be treated as suspect.
  • A persistent weak layer is present near the bottom of the snowpack in the northern half of the region (e.g., Duffey, Hurley). The weak layer of sugary faceted grains exists around a hard melt-freeze crust from mid-November. This is an indicative snowpack setup for large and destructive avalanches. The likelihood of human-triggered avalanches decreases as the layer gets deeper but the consequence of triggering it would be severe.
  • There are currently no concerns deeper in the snowpack near Coquihalla summit.

Terrain and Travel

  • Recent new snow may be hiding windslabs that were easily visible before the snow fell.
  • If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
  • Watch your sluff: it may run faster and further than you expect.

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Unconsolidated fluffy snow of the recent storm sits on a snow surface that was wind affected by moderate to strong southerly wind. Slabs will likely be more sensitive in lee terrain features in the alpine and around treeline. The most recent unconsolidated snow will hide slabs which will make navigating around wind slabs more tricky.

Aspects:

All aspects.

Elevations:

All elevations.

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible

Expected Size

2 - 3.5

Two layers that cause concern:

  • In many parts of the region, with the exception potentially being near Coquihalla summit, recent storm snow may overly a touchy surface hoar layer found around treeline elevations in sheltered areas. This layer has produced large avalanches that have propagated far.
  • In the north half of the region, a weak layer is buried near the bottom of the snowpack. This layer has been responsible for recent large, destructive avalanches.

The likelihood of humans triggering these layers remains elevated due to the recent load applied to them. Storm slab avalanches could step down to these layers.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Jan 13th, 2020 5:00PM