Avalanche Forecast

Issued: Jan 24th, 2017 5:00PM

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

Avalanche Canada jlammers, Avalanche Canada

For most of the region, isolated wind slabs are the main concern.If you are in the far north of the region around Valemount and Blue River, a persistent slab problem exists and the Cariboos bulletin is more applicable. Click here for more details.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Expect a mix of sun and cloud for the forecast period. Ridgetop winds should remain mainly light with daytime freezing levels hovering around 800m.

Avalanche Summary

In the south of the region where wind slabs are the primary concern, avalanche activity tapered-off somewhat on Monday. There were, however, a few exceptions in the Selkirks. Just to the west of Kinbasket Lake, a size 2 slab avalanche was skier-triggered on a south-facing alpine slope. A recently buried surface hoar layer is though to be the culprit in the event. In the same part of the region, a skier triggered a size 1.5 wind slab on a northeast facing treeline feature. Nobody was hurt in either of these slides. An anomalous size 3 deep persistent slab was also triggered by natural cornice fall in the Adamants.  The avalanche failed on glacier ice, was 200m wide, and ran 600m. A few solar-triggered slab avalanches to size 3 were also noted.On Sunday in the far north of the region near Blue River, a snowmobiler triggered a size 3 persistent slab avalanche on a south aspect in the alpine which released on surface hoar down 100 cm. Check out the MIN post for more details. In this part of the region, a more widespread persistent slab problem exists. If you are recreating in the Monashees near Blue River or Valemount, use the Cariboos bulletin for more representative conditions.

Snowpack Summary

30-60 cm of recent storm snow typically overlies the variable mid-January interface with the largest snowfall amounts in the north of the region. The buried interface consists of wind affected surfaces in exposed terrain, surface hoar up to 10 mm in sheltered areas, and/or widespread faceted old snow. The bond between the new snow and the old surface has generally gained a lot of strength with the colder temperatures that followed the storm but weaknesses may still be lingering, especially where surface hoar is preserved. Strong southwest winds during the storm had redistributed the new snow and developed wind slabs in leeward terrain features. Isolated moderate outflow winds may have more recently resulted in reverse wind loading.The mid-December facet/surface hoar persistent weak layer can be found buried 100-120 cm deep. This layer is now dormant in the south of the region but is still a real concern in the far north of the region in the mountains around Blue River and Valemount. It is highly recommended to investigate this layer before committing to any large, unsupported features.

Problems

Wind Slabs

An icon showing Wind Slabs
Stubborn old wind slabs may still be reactive to human triggering in steep wind loaded terrain features. In some areas, moderate outflow winds may have caused reverse loading and formed thin new wind slabs.
Be cautious as you transition into wind affected terrain.Avoid areas where the surface snow feels stiff or slabby.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 25th, 2017 2:00PM

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