Avalanche Forecast

Issued: Jan 6th, 2016 7:37AM

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

Avalanche Canada triley, Avalanche Canada

I bumped the alpine danger up a notch to Considerable for Thursday due to forecast new snow and wind continuing to develop wind slabs over an easy sliding layer.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Some moisture trapped in the south to north flow coming out of Washington State should bring 3-5 mm of precipitation (5-10 cm of snow at treeline) overnight, and another 3-5 mm of precipitation during the day on Thursday. Winds are expected to be light from the southeast and alpine temperatures should remain around -5. High pressure with light winds and cooler air should move into the region from the north on Friday. Some flurries may continue on Friday and Saturday with periods of broken skies and alpine temperatures around -10. The north of the region may be closer to -15 in the alpine by Saturday.

Avalanche Summary

Thin new windslabs were reported releasing up to size 1.0 in the north of the region. One third hand report of a remotely triggered size 2.0 wind slab on a North aspect at 2440 metres near Panorama.

Snowpack Summary

Light new snow falls have buried large surface hoar on all aspects at and below treeline and on shaded aspects in the alpine. Easterly winds associated with the new snow may have disturbed surface hoar in the alpine. New snow on southerly aspects may be sitting on a sun crust and/or surface hoar, providing an easy sliding layer. The new snow should be mostly unconsolidated except where it has been re-distributed by the wind. Fresh wind slabs may be sitting on 10-20 cm of facetted snow on all but steep solar exposed aspects. In the southern Purcells, (west of Kimberley), a prominent layer of buried surface hoar has shown to be reactive to human triggers. In this part of the region, it's buried down 40 cm with a cohesive slab above it. Shallow snowpack areas and moraine features may have weak facetted snow near the ground that will require time and some warming to strengthen.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs are expected to continue to develop with forecast new snow and wind. Buried surface hoar and loose facetted snow may act as an easy sliding layer.
Be cautious as you transition into wind affected terrain. >Use ridges or ribs to avoid pockets of wind loaded snow. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Deeply buried weak surface hoar has not resulted in any reports of deep slab avalanches since the new year. This problem has become less likely, but still needs to be considered when choosing terrain.
Dig down to find and test weak layers before committing to a big line. >Avoid exposed alpine faces, especially in the north of the region.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved, especially in the south of the region.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Jan 7th, 2016 2:00PM

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