Archived

Avalanche Forecast

Dec 2nd, 2016–Dec 3rd, 2016

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: 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.

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

Avalanche 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