Archived

Avalanche Forecast

Jan 8th, 2017–Jan 9th, 2017

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

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

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Columbia.

Wind is driving the avalanche danger on Monday. I would expect to find touchy wind slabs on lee features below ridgetops and good skiing in sheltered terrain.

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

MONDAY: Snow beginning Sunday evening and is expected to accumulate to 15-20 cm by Monday afternoon. Moderate southwesterly ridgetop winds, and temperatures around -10.TUESDAY: Mix of sun and cloud, moderate northwesterly ridgetop winds, and temperatures around -15.WEDNESDAY: Mostly sunny with cloudy periods, light northwesterly ridgetop winds, and temperatures around -15.

Avalanche Summary

On Saturday, one natural and several human triggered size 1 wind slabs were reported on a variety of aspects. I expect human triggered wind slab activity to increase on Monday with the forecast new snow and wind.

Snowpack Summary

Forecast 10-20 cm of new snow by Monday afternoon and moderate southwest winds are expected to create fresh wind slabs on lee features at treeline and above. Recent snow has also covered old, thicker wind and hard slabs from previous wind events. The mid-December facet/surface hoar persistent weakness can be found buried 70-120 cm deep and is generally giving hard resistant or no results in snowpack tests. However, we are still receiving occasional reports of sudden results, suggesting that it has to potential to propagate into a large avalanche if triggered, particularly in shallow spots where this layer closer to the snow surface. The lower snowpack is well bonded and features a thick rain crust near the ground.

Avalanche Problems

Wind Slabs

Expect wind affected terrain to be significantly more reactive than sheltered areas. Watch for sings of instability such as whumphing, cracking, and recent avalanches.

Avoid areas where the snow feels stiff or slabby.Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2