Avalanche Forecast

Issued: Dec 2nd, 2016 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

As the storm intensifies avalanche danger will increase rapidly. Consider what terrain is above you; avalanches starting in the alpine may run well into the alder! Space out when crossing run outs and regroup in safe spots.

Summary

Weather Forecast

An intense storm is headed our way. The timing is uncertain but we expect flurries with ~ 7cm today. The storm will intensify this afternoon with winds increasing to strong and up to 10cm overnight. Saturday will follow a similar pattern, with ~5cm during the day followed by another 10cm overnight. Sunday will clear and temps will plummet.

Snowpack Summary

10-20cm of powder overlies settled snow & windslabs in the alpine. The Nov 13 crust is buried ~60 and 100cm deep. In most areas the crust seems to be bonding well but is of most concern on S'ly aspects. Tests on a SW aspect, 2075m indicated that the crust may be triggered by light loads and that it is capable of propagating into a large avalanche.

Avalanche Summary

Light winds and only small amounts of snow over the past few days has resulted in little natural avalanche activity. Natural avalanches up to size 2 have been observed from steep, unskiable terrain. There have also been a few reports of ski cuts causing small loose avalanches. We expect avalanche activity to increase rapidly as the storm arrives.

Confidence

Timing of incoming weather systems is uncertain

Problems

Persistent Slabs

Forecast snow and wind might make a crust buried up to 1m deep more reactive and unpredictable. Test results show variability: in some areas it is unreactive and in others it may be triggered by light loads (you!) and produce large avalanches.

Choose regroup spots carefully.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Loose Dry

We are expecting up to 30cm of snow by Sunday. This will add to ~20cm of powder sitting on the surface. Expect sluffing and loose avalanches to be triggered when skiing steep slopes. The loose snow also hides tree wells; buddy up!

Be aware of party members below you that may be exposed to your sluffs.Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

Pockets of windslab at ridgecrests and on lee features are buried under low density snow and may be hard to identify.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Watch for signs of instability such as whumpfing, or cracking.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 3rd, 2016 8:00AM