Archived

Avalanche Forecast

Jan 14th, 2013–Jan 15th, 2013

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

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

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: Glacier.

There is a lot of variability in the upper snowpack; skier triggering is possible on specific terrain. A rapid rise in temperatures is forecast to begin later today, and clear skies tomorrow. Avalanche danger will increase with the warmth and solar.

Weather Forecast

The warm front passage is bringing clouds, light snow, and temps will start to rise, with warmer temps in the alpine reaching -5 today. Upper level winds (3000m) are N'ly, while lower level winds (see weather stations) remain S'ly. Tues and Wed expect strong solar and winds, with alpine temps to 0. This rapid change in temp will increase danger.

Snowpack Summary

A 30-60cm slab overlies the Jan.4 persistent layer. The distribution of this layer is variable but tests and a Sa yesterday indicate it is triggerable. Our main concern is on steep S'ly slopes where facets or surface hoar overlie a crust. In sheltered areas on all aspects between 1500 and 1700m it consists of surface hoar. New windslabs have formed

Avalanche Summary

Yesterday, skiers accidentally triggered a size 2.5 avalanche while bootpacking up the SE face of Rogers. It failed on facets on the Jan 4 crust, and propagated 30m upslope. It was 35m wide, 300m long with 1-2m deep debris. One person was involved but was uninjured. There have been no new natural avalanches observed since Jan 10th.

Confidence

Timing of incoming weather systems is uncertain

Avalanche Problems

Persistent Slabs

A cohesive slab overlies a persistent weak layer. Variable distribution and composition makes this layer difficult to predict. Tests on this layer indicate it is skier triggerable and observations indicate it is most reactive on steep S'ly aspects.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Choose well supported terrain without convexities.

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 3

Wind Slabs

Upper level winds from the N have created windslabs on S-SE slopes in the high alpine. Winds around 2000m are from the south, loading N-NE slopes. Watch for windslabs in the alpine; if triggered they may step down to the persistent slab.

Be cautious as you transition into wind affected terrain.Enter your line well below ridge crests to avoid wind loaded pillows.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2