Avalanche Forecast

Issued: Apr 19th, 2013 10:51AM

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 swerner, Avalanche Canada

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

An upper trough will move through the Interior tomorrow. The NW flow will bring cooler, dryer air to the region with some pulses of precipitation. Saturday: Overcast with some clearing in the Cariboo's  later in the day. Light-moderate precipitation amounts. Ridgetop winds blowing moderate from the NW. Freezing levels near 1000 m.Sunday/Monday: A ridge of high pressure will bring a mainly sunny skies, with cooling and dryer conditions. Freezing levels will be near 1200 m during the afternoon and falling to valley bottom overnight

Avalanche Summary

On Friday a skier triggered size 1.5 slab avalanche was reported. This occurred on an East aspect at 2250 m. Loose wet natural avalanche activity also occurred on a variety of aspects and elevations during daytime warming.

Snowpack Summary

Up to 15 cm of new snow sits on a variety of old surfaces. These include melt-freeze crusts on solar aspects and dry snow with some surface facts and surface hoar on Northerly aspects. Wind slabs have built on lee slopes and behind terrain features. Cornices are huge and remain a concern, threatening slopes below.Buried 60-100 cm down, exists an interface of crusts and buried surface hoar. This is mainly found at upper elevations on all aspects. It seems to be slowly gaining strength, yet this interface has recently become reactive in regions further south. I would remain suspicious, especially of large, steep high-alpine slopes. Dig down, and test layer of concern.

Problems

Wind Slabs

An icon showing Wind Slabs
New snow and moderate winds have built wind slabs on lee slopes and behind terrain features. Large, looming cornices exist on ridgelines and pose a threat to slopes below. Keep your distance from them.
Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
A weak interface is buried about a metre down. A smaller avalanche stepping down, cornice fall, the weight under a snowmobile, or the weight of a person from a thin-spot trigger point could trigger a large and destructive avalanche.
Be aware of thin areas that may propagate to deeper instabilites.>Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Apr 20th, 2013 2:00PM