Avalanche Forecast

Issued: Jan 4th, 2015 7:59AM

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

Avalanche Canada triley, Avalanche Canada

The storm is moving across the interior regions tonight resulting in HIGH avalanche danger by morning. Heavy snowfall and strong winds are expected to develop new storm slabs.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A moist Pacific storm is moving across the interior mountain regions from the Southwest on Sunday, and is expected to collide with cold arctic air that is anchored on the East side of the Rockies. Areas where the warm moist air meets the cold air should result in moderate to heavy snowfall. The cold air has setup in a Northwest to Southeast tilt which should result in greater amounts of snow in the South and West of the region, and continued cold air with flurries or light snow in the North and East of the region. Overnight snowfall amounts should vary from 5-15 cm combined with strong Southwest winds. On Monday expect moderate Westerly winds and 3-5 cm of snow. Overnight and into Tuesday morning expect 5-15 cm, and another 3-5 before the storm ends on Wednesday.

Avalanche Summary

No new avalanches reported. Expect the developing new storm slab to result in easy triggering or natural avalanches.

Snowpack Summary

New snow and moderate Southwest winds developed isolated pockets of touchy windslab in the alpine and at treeline. Since previous winds were from the north or northwest, wind slabs should be suspected on a wide variety of aspects in exposed terrain. A thin layer of surface hoar with variable distribution was buried on December 27th by about 5-10 cm of light dry snow. As more snow accumulates, this interface could become one to watch. Deeper, at about 40-60 cm below the surface, a persistent crust/surface hoar layer from mid-December can be found.  This persistent slab problem is reasonably widespread across the region and is not expected to improve quickly. A deeper crust/facet layer which formed early in the season may still be triggerable from thin or rocky snowpack areas.

Problems

Storm Slabs

An icon showing Storm Slabs
Forecast new snow and strong winds are expected to develop a new storm slab. The new storm slab may release naturally or with light additional loads like a skier/rider.
Give cornices a wide berth when travelling on or below ridges.>Travel on ridgetops to avoid wind slabs on slopes below.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
The developing storm slab will add to the load above the mid-December persistent weak layer. This may not be enough load to trigger naturally, but may increase propagation distance and the likelihood of remote triggering.
Stick to small features with limited consequence and be aware of what is above you at all times.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Jan 5th, 2015 2:00PM

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