Regions
Vancouver Island.
Potentially the most active avalanche cycle of the season has taken place here on Vancouver Island. Multiple reports of Natural avalanches and skier triggered avalanches on Treeline and Alpine Terrain in the Size 1- Size 2 category. We are not out of the "woods" or high avalanche hazard yet however as the mountains will continue to be subjected to a great deal of rainfall late into the evening of Friday January 31st.
Past Weather
Great skiing and snowmobiling until Thursday-Friday's rainfall event. Major rain in excess of 100mm has fallen throughout Vancouver Island including the Alpine.
Weather Forecast
The weather trend will improve avalanche conditions in the long term but we still need to wait it out another 24hrs (short term) before that stability is restored. Saturday 6- 9 mm Rain, 6 cm - 17 cm Snow, Winds Moderate to Strong from the West, Freezing level dropping from 1,700M early in the morning to 500M by dusk.Sunday 7 - 16 cm Snow, Winds Moderate and shifting from the SW to NW, Freezing level 500 meters.Sunday 0 - 3 cm, Winds Moderate to Light from the West, Freezing level 550 meters
Terrain Advice
As a result of this major rain event, Saturday’s Avalanche Hazard is set to CONSIDERABLE (Human Triggered Avalanches Likely, natural avalanches possible). 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 Saturday, specific regions of Vancouver Island may undergo a major cooling event, moderate snowfall and strong winds. This general "extreme" weather pattern and shifting in terms of precipitation type, air temperature fluctuation and wind speeds is such that Saturday will still require a great deal of prudence when travelling onto slopes steeper than 30 degrees. This weekend, be aware of visible (snow cracking underfoot/adjacent your sled) and/or audible (whumpfing) clues 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 (especially Saturday). Fortunately, the cooling trend will help to consolidate the snowpack and on Sunday-Monday, steeper terrain beyond 30 degrees will become more settled and be potentially more stable if forecast models hold true and the air temperatures drop way down closer to Sea Level. Check the website ATES PLANNING section for Simple Terrain options on our website if you intend to travel Saturday in the backcountry. On Sunday and Monday, avalanche terrain could include bigger objectives due to major air temperature cooling for the majority of Vancouver Island. Nonetheless, it is still important to mitigate slope angle and risk exposure to yourself and your group while travelling / recreating in avalanche terrain.
Snowpack Summary
The Not So Good News: 1 week ago (January 23rd) Vancouver Island received a major rainfall event. Subsequent snowfall was deposited onto this January 23rd rain crust and over the course of this past week we underwent our most substantial natural and human triggered avalanche cycle of the winter. In the short term, Friday January 31st rain event has further exacerbated the instability on this upper snowpack Rain crust as it has added major new weight/load to the weak layer. Treat Saturday as the period necessary to allow for stability to return into the snowpack thanks to the cooler cold front that arrives in the early hours Saturday morning. The Good News: Sunday and Monday should show a more predictable Vancouver Island snowpack with improved consolidation thanks in part to the rain and the major cooling trend.
Snowpack Details
- Surface: Saturday 15-25 cm of wet moisture laden snow. Sunday and Monday (6 - 16 cm of light dry powder snow)
- Upper: A Rain crust responsible for a large number of natural and human triggered avalanches
- Mid: Well bonded midpack that does include two weaker layers (Facet on Ice Crust layers)
- Lower: Well Settled
Confidence
High - Weather models in agreement, sufficient field weather and snowpack observations
Problems
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.