Regions
Vancouver Island.
On Wednesday : Several size 1 (ski cut) avalanches reported at Treeline elevation on the recent storm snow interface, remote triggering was also reported (Size 1's) at Treeline elevation.
Past Weather
Relatively consistent below freezing temperatures at Treeline elevation coupled with consistent moderate snowfall have made for great snowmobiling and skiing. Wednesday's air temperature rose and as a result so too did the avalanche hazard.
Weather Forecast
The weather pattern is about to get dynamic in terms of precipitation, wind and air temperature fluctuation the next several days. Thursday 2- 12 mm Rain, 4 cm - 12 cm Snow, Winds Extreme from the South, Freezing level 2,100 meters.Friday 70 - 130 mm, Winds Extreme from the South, Freezing level 2500 meters.Saturday 2 - 16 cm, Winds Moderate from the West, Freezing level 550 meters.
Terrain Advice
On Thursday, Natural Avalanches possible, Human triggered avalanches likely in Alpine and Treeline on unsupported terrain. There is an extreme amount of precipitation expected Friday. As a result of this major rain event, Friday's forecast Avalanche Hazard is set to HIGH (Human Triggered Avalanches Very Likely, natural avalanches Likely). Be aware as you move through the terrain for shooting cracks, snow "pin wheeling" and signs of instability (including new avalanches) especially at Treeline and Alpine elevation bands. On Friday, it will be wise to avoid all avalanche terrain and allow for cooling air temperatures to settle instabilities that will occur on Friday and into Saturday if the extreme rain event occurs in your area.On Thursday if visible (snow cracking underfoot/adjacent your sled) and/or audible (whumpfing) clues exist in your area, it will be important to find lower angle terrain (generally under 30 degrees) and or ski/sled in more densely vegetated (treed) areas away from these obvious clues of snowpack instability. Check the website ATES PLANNING section for Simple Terrain options on our website. On Friday, avoid all avalanche terrain due to extreme weather (Wind/Rain) forecasted for the majority of Vancouver Island.
Snowpack Summary
Moderate rates of precipitation in the form of snow have occurred on Vancouver Island for the past several days. As a result, the upper snowpack contains several storm snow layers that are consolidating due to favourable air temperature. The mid and lower snowpack are extremely well consolidated due to the below freezing temperatures we have seen throughout the majority of January. The generally high moisture content in the snowpack currently is such that it has allowed for favourable consolidation (rounding).
Snowpack Details
- Surface: Multiple storm snow and wind events have created a 30cm-50 cm surface snowpack of rounding snow
- Upper: Well bonded and dense moisture laden snowpack
- Mid: Well bonded mid-pack that does include two weaker (PWL) layers (Facet layers) both un-reactive to testing
- Lower: Well Settled
Confidence
High - Weather models in agreement, sufficient field weather and snowpack observations
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.