Avalanche Forecast

Issued: Feb 16th, 2019 4:19PM

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

mconlan, Avalanche Canada

Cariboos.

Persistent slab avalanches continue to be triggered by humans. The consequence of being involved with one is high.

Summary

Confidence

High -

Weather Forecast

SATURDAY NIGHT: Mostly cloudy with isolated snowfall, trace accumulation, light to moderate northeast wind, alpine temperature -13 C.SUNDAY: Mostly clear skies, moderate northeast wind, alpine temperature -16 C.MONDAY: Mix of sun and cloud, light to moderate west wind, alpine temperature -15 C.TUESDAY: Cloudy with light snowfall, accumulation 1 to 5 cm, moderate west wind, alpine temperature -14 C.

Avalanche Summary

Two small to large (size 1 to 2) persistent slab avalanches were triggered by skiers on Friday. They were 50 to 70 cm deep and released on the mid-January surface hoar layer described in the Snowpack Summary. The occurred at treeline and alpine elevations on north to northwest aspects.

Snowpack Summary

Recent strong northeast wind has blown loose snow into wind slabs in exposed areas.A touchy weak layer responsible for surprise avalanches and several close calls lies approximately 30 cm below the surface in shallow snowpack areas and 60 cm or more in deeper areas. This weak layer of surface hoar and faceted grains was buried mid-January. On southerly aspects, it lies on top of a melt-freeze crust. It is most prevalent at treeline and below treeline elevations, but there have been a few reports of its presence in sheltered areas in the alpine. This layer is shallow enough to be triggered but deep enough to produce large avalanches.Deeper layers in the snowpack are not a factor at this time.

Problems

Persistent Slabs

Approximately 50 cm of snow sits above a persistent weak layer of surface hoar that was buried in mid-January. The surface hoar may sit on a melt-freeze crust on south aspects. This layer continues to be reactive to human triggering.

Avoid steep, open and/or sparsely treed slopes at and below treeline.Use conservative route selection, choose moderate angled terrain with low consequence.Be aware of the potential for wide propagation.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Wind Slabs

Most of the region has been hit hard by winds, which formed wind slabs in the lee of terrain features on a variety of aspects. If triggered, there is potential for a wind slab avalanche to step down to a buried persistent weak layer.

If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 17th, 2019 2:00PM