Avalanche Forecast

Issued: Jan 3rd, 2015 8:45AM

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

Avalanche Canada jlammers, Avalanche Canada

If Sunday's winds are stronger than forecast, the Avalanche Danger in the alpine may rise to Considerable. Watch for blowing snow at high elevations.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

On Sunday we can expect very light flurries, moderate northwesterly ridgetop winds, and alpine temperatures of about -18.  Light snowfall is expected by Sunday night, and should continue until Tuesday as a pacific frontal system pushes eastward. With this system, we can expect strong westerly winds with freezing levels staying at valley bottom.

Avalanche Summary

No new avalanches have been reported, although I suspect there was some wind slab activity in response to Friday's wind event.

Snowpack Summary

Snow surfaces are variable with northerly, wind exposed aspects showing firm wind pressing, or a scoured exposed crust. More sheltered locations have up to 30 cm of low density, faceted snow. In the alpine and at treeline, strong northerly winds have transported this snow into stiff wind slabs on opposite slopes. Up to 70 cm below the surface you will likely find a hard, thick crust which formed mid-December. At higher elevations this crust has facets (sugary) snow above it and well-preserved surface hoar up to 10 mm in size in sheltered locations at treeline and below. Where the crust exists, it may be bridging triggers from penetrating to deeper persistent weaknesses. However, on high alpine slopes above where the rain crust formed, or in areas where rain didn't occur, deeply buried facets may still be susceptible to triggering, especially in thinner snowpack areas.

Problems

Wind Slabs

An icon showing Wind Slabs
Between 15 and 30 cm of low-density snow has been transported by strong swirling winds into hard wind slabs. Initially winds blew from the northwest, but then switched to the southeast, which means wind slabs may be found on a variety of aspects.
Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
A crust which formed in December should remain on your radar as it has recently produced large avalanches in the south of the region.  Dig down and test weak layers before committing to a line.
Make observations and assess conditions continually as you travel.>Stick to well supported terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Jan 4th, 2015 2:00PM

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