Register
Get forecast notifications
Create an account to receive email notifications when forecasts are published.
Login
Archived

Avalanche Forecast

Jan 21st, 2017–Jan 22nd, 2017
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
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.

Recently touchy storm slabs are expected to remain reactive to human triggering on Sunday. A persistent weakness in the snowpack has also recently resulted in some very large avalanches. Conservative terrain selection remains critical.

Confidence

Moderate - Due to the number of field observations on Saturday

Weather Forecast

Mostly cloudy conditions are expected on Sunday with the possibility of light flurries. Alpine wind is expected to be moderate from the south and afternoon freezing levels are forecast to be around 1000 m. A mix of sun and cloud is forecast for Monday and Tuesday with periods of light flurries possible. Alpine winds are expected to be mainly light and afternoon freezing levels are forecast to be between 500 and 1000 metres.

Avalanche Summary

On Friday, a natural size 3 storm slab avalanche was observed on a west aspect at 2500 m in the northern Monashees. This occurred on a convex glacial feature and the slab was 80 cm thick. An avalanche accident was reported in the Allen Creek riding area and up to 6 people may have been buried but details are still limited. Three large remotely triggered avalanches were also reported on Friday. Two of these were expected to have released on the mid-January layer below the recent storm snow. The third released on mid-December layer down around 80 cm and was triggered from 100 m away. Explosives triggered four persistent slab avalanches size 2.5-3 which are expected to have released on the mid-December layer down around 1.5 m. On Sunday, the recent storm snow is expected to remain reactive to human triggering in wind loaded terrain and steep unsupported or convex features. The mid-December weak layer is a real concern for the region and persistent slab avalanches remain possible. It may be possible to trigger this layer in shallow snowpack areas and smaller storm slab avalanches could step down to this layer in all areas.

Snowpack Summary

40-60 cm of recent storm snow typically overlies the variable mid-January interface which consists wind affected surfaces in exposed terrain, surface hoar up to 7 mm in sheltered areas, and/or widespread faceted old snow. Strong southwest winds during the storm have redistributed the new snow and developed wind slabs in leeward terrain features. In deeper snowpack parts of the region, the mid-December facet layer typically lies around 1.5 m below the surface. In shallower areas, particularly those in the southeast (Allen Creek), North (Sugar Bowl) and likely some western areas around Quesnel and Barkerville, the snowpack is likely a lot more suspect, with a thicker, more pronounced facet layer buried only 50-60 cm below the surface.

Avalanche Problems

Storm Slabs

The recent storm snow is expected to remain sensitive to human triggering in wind loaded terrain features and steep unsupported or convex features. In some areas, buried surface hoar may increase the reactivity of these slabs.
Be cautious as you transition into wind affected terrain.Watch for signs of instability such as whumpfing, or cracking. Avoid areas where the surface snow feels stiff or slabby.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Persistent Slabs

Recent storm loading combined with warmer temperatures has woken up the mid-December weak layer and several large persistent slab avalanches have been reported in the last couple days.
Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Avoid shallow snowpack areas where triggering is more likely.If triggered, storm slabs or cornices may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4