Archived

Avalanche Forecast

Dec 9th, 2015–Dec 10th, 2015

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

The warmth continues, and with it, the high danger. Let the snowpack adjust to the new load before sticking your neck out.

Weather Forecast

Freezing levels will remain around 1500m today. 10-15cm of snow will fall in the area, with moderate to strong SW winds at ridge-top. A weak ridge will bring a brief respite tonight, lowering freezing levels below 1000m. Flurries with minor accumulations are expected tomorrow.

Snowpack Summary

Storm snow has created a 20-30cm surface slab. The widespread Dec 2 surface hoar layer is down 40-70cm and is reactive to human loading. Recent snowpack tests showed the early November surface hoar layers reactive to heavy loads, popping off the columns in a sudden planar manner. This suggests avalanches could step down to deeper layers.

Avalanche Summary

Artillery avalanche control yesterday produced numerous avalanches up to size 4. Numerous natural avalanches up to size 3 were observed in the highway corridor before avalanche control commenced, earlier in the day. We suspect there were numerous natural avalanches in the backcountry yesterday, continuing today with the warm temperatures.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

The Dec 2nd surface hoar / crust layer has reached critical load. Expect the storm slab to be reactive to both human and natural triggering.

Watch for whumpfing, hollow sounds, and shooting cracks.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 3

Wind Slabs

Strong S winds formed wind slabs on N aspects in the alpine and tree-line. In some locations these slabs will be resting on the Dec 2nd surface hoar layer and will be sensitive to human triggering.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Minimize overhead exposure during periods of heavy loading from new snow, wind.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Loose Dry

There is plenty of loose, unconsolidated snow available to sluff around you. Be aware that it can easily accumulate to a critical load and trigger underlying slabs, especially the Dec 2 surface hoar / crust layer.

Be aware of party members below you that may be exposed to your sluffs.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2