Avalanche Forecast

Issued: Feb 10th, 2018 4:36PM

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

Avalanche Canada jmcbride, Avalanche Canada

Heads up! Large avalanches have the potential to reach run-out zones. Be aware what, or who, may be above you.Special Avalanche Warning in effect for the interior ranges. Copy this address to view details: http://bit.ly/2nSOUyX

Summary

Confidence

Moderate -

Weather Forecast

SUNDAY: Mix of sun and cloud. Ridge wind light to moderate, east. Temperature -10. Freezing level valley bottom.MONDAY: Mostly sunny. Ridge wind light, north. Temperature -8. Freezing level valley bottom.TUESDAY: Cloudy, light flurries. Accumulation trace. Ridge wind light to moderate, southwest. Temperature -8. Freezing level 800 m.

Avalanche Summary

There are no confirmed reports of avalanches from Friday, however is SAR responding in an incident involving a snowmobiler in the southern Slocan Valley that appears to be avalanche related.On Thursday, several large and destructive natural slab avalanches occurred through the region up to size 2.5 on all aspects and elevations. Avalanche control using explosives triggered numerous loose wet avalanches up to size 2 and a significant size 3 storm slab avalanche. These were reported from SE-SW slopes above 1900 m. Earlier in the week, two very large destructive avalanches up to size 3.5 were triggered remotely (from a distance) with crown depths up to 200 cm. At least one of these avalanches ran full-path, destroying mature trees.Natural avalanche activity will likely taper off through the weekend with colder temps; however, slopes will remain primed for human triggers.

Snowpack Summary

Storm snow accumulations from the past week vary from 10-45cm across the region at upper elevations. In the alpine this new snow has been redistributed to leeward slopes from strong northwest winds. Below 1800 m, up to 5 cm of low density snow covers a thin crust. This now brings 1- 2 m of settled snow sitting on three significant surface hoar/ crust layers that were formed early to mid-January, and back in December. Near the base of the snowpack a crust/ facet interface exists and will likely haunt us all season. These persistent weak layers that lurk within the snowpack are reactive, producing large and destructive avalanches. The snowpack is extremely complex and requires respect and diligence at this time.

Problems

Wind Slabs

An icon showing Wind Slabs
Storm slabs are reactive. Natural avalanche activity may taper off, but slopes are primed for human triggers. Be aware that a slab or loose snow release near the surface could also step down to deeper layers in the snowpack.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Persistent Slabs

An icon showing Persistent Slabs
The snowpack is complex and continues to produce very large avalanches on weak layers now deeply buried below the surface.
Be mindful that deep instabilities are still present and have produced recent large avalanches.Avoid shallow snowpack areas where triggering a deep layer is more likely.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Valid until: Feb 11th, 2018 2:00PM

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