Archived

Avalanche Forecast

Jan 6th, 2015–Jan 7th, 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

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

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Cariboos.

High avalanche danger is expected to continue for another day due to new storm slabs, high freezing levels, and above freezing air trapped in the alpine.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Snow ending overnight with a chance of flurries during the day Wednesday. Light SE winds overnight becoming moderate Southwest during the day Wednesday as freezing levels rise up to 1200 metres and some above freezing air becomes trapped between 2000 and 2500 metres. Gradual clearing with some convective snow flurries on Thursday and freezing levels dropping down below 1000 metres. Mostly clear skies with light winds and no precipitation on Friday.

Avalanche Summary

Some large settlements and skier triggered avalanches to size 1.0 were reported from Monday. I suspect the new storm slab has settled with the warming temperatures and may become easier to trigger.

Snowpack Summary

10-20 cm of new snow overnight has developed a storm slab that is 40-60 cm thick that is sitting above a mix of old surfaces including wind slabs, old storm slabs, and pockets of surface hoar. Warm air in the alpine and at treeline has settled the new storm slab into a cohesive slab that is easier to trigger and may allow for longer fracture propagations. Below the storm slab there is a weak layer of surface hoar and crust that was buried in mid-December that continues to be a concern for human triggering. The mid-December weak layer may be buried up to 100 cm deep. Avalanches releasing on this layer may be large and destructive.

Avalanche Problems

Storm Slabs

The new storm slab may become more likely to trigger from light additional loads due to the warm air in the alpine rapidly settling the new snow.

The new snow will require several days to settle and stabilize.>Choose well supported terrain without convexities.>Good day to make conservative terrain choices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 4

Persistent Slabs

The mid-December persistent weak layer may release naturally due to the new load of storm snow, or be triggered by storm slab avalanches in motion.

Stick to small features with limited consequence and be aware of what is above you at all times.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 5