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Avalanche Forecast

Dec 21st, 2018–Dec 22nd, 2018
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
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

Regions: South Coast Inland.

Recent slabs formed at high elevations may still be reactive to human traffic, especially in lee terrain features. For the north of the region, be diligent around treeline where a buried weak layer may still linger.

Confidence

Moderate.

Weather Forecast

FRIDAY NIGHT: Mostly cloudy, freezing level below valley bottom. SATURDAY: Cloudy with light snowfall, accumulation 5cm, moderate southwest winds, alpine temperature -7°c, freezing level below valley bottom. SUNDAY: Cloudy with snowfall, accumulation 5 to 10cm, moderate southwest winds, alpine temperature -5°c, freezing level 600m. MONDAY: Clearing over the day, light south winds, alpine temperature -8°c, freezing level 800m.

Avalanche Summary

A natural storm slab avalanche cycles occurred on Thursday in the north of the region, with large avalanches up to size 3. This is similar to cycles that occurred during previous storms within the past week (see description and photos here). Few avalanches were observed in the south of the region on Thursday.

Snowpack Summary

Around 30 to 40 cm of snow fell in the region on Thursday at high elevations. Below about 1800 m expect to find a melt-freeze crust due to rain. At high elevations, expect to find deeper slabs in the lees of terrain features due to strong variable winds. In the north portion of the region and possibly the far south, a weak layer of facets and surface hoar lies below all this storm snow, around 120 cm deep. The weak layer appears most prominent around treeline, up to 2000 m. While the layer is likely gaining strength, field observations show that slab avalanches remain possible on this layer where it exists. Near the base of the snowpack, a crust exists with weak and sugary facets beneath it. This could potentially still be of concern in high north-facing aspects where the snowpack rests on very smooth ground cover.

Avalanche Problems

Wind Slabs

The recent snow will likely need a bit of time to bond to previous surfaces, particularly near ridges where deeper and touchier deposits may linger.
Use ridges or ribs to avoid pockets of wind-loaded snow.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

A weak layer buried approximately 120 cm has the potential to produce large avalanches. This layer is likely most problematic in the north section of the region and possibly the far south, around treeline elevations.
Use conservative route selection and choose moderate-angled slopes with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3