Avalanche Forecast
Dec 20th, 2018–Dec 21st, 2018
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
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
Regions: South Coast Inland.
The sun should shine on Friday, showcasing snow distribution and avalanche activity from Thursday's storm. Be wary of the bonding of all the recent snow, especially in lee terrain features near ridges, where snow deposits will be deep.
Confidence
Moderate - Due to the number of field observations.
Weather Forecast
THURSDAY NIGHT: Cloudy, freezing level dropping from 1000m to below valley bottom. FRIDAY: Partly cloudy, moderate northwest winds, alpine temperature -12°c, 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 1000m.
Avalanche Summary
Natural storm slab avalanche cycles have occurred during each storm within the past week (see description and photos here). It is likely that a natural cycle occurred again on Thursday during the storm. Clearing skies on Friday should allow for views of previous avalanche activity.
Snowpack Summary
Around 30 to 40cm of snow fell in the region on Thursday with associated strong southerly winds. Deeper snow deposits are likely in the lees of terrain features. This sits on around 1 to 2m of storm snow that has fallen in the past two weeks. Below 1500m, Thursday's precipitation mostly fell as rain. In the north portion of the region, a weak layer of facets and surface hoar lies below all this storm snow, around 120cm deep. The weak layer appears most prominent around treeline, up to 2000m. 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
Storm Slabs
Around 30 to 40 cm of snow fell on Thursday with associated strong southerly winds. The deepest deposits will be in lee terrain features near ridges. Expect this recent snow to be reactive to human traffic.
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind-loaded snow.
Aspects: All aspects.
Elevations: All elevations.
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 around treeline elevations.
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3