Regions
Vancouver Island.
See below for Confidence details:
Avalanche Summary: Several size 1 and size 2 natural slab avalanches have been reported over the week. Several size 0.5 to size 1 skier triggered avalanches also reported.
Confidence details tab is currently under maintenance- posting Confidence details here:
High confidence: Based on extensive data collection all week as well as many people submitting observations from the field. Monday's confidence is Moderate.
The elevated avalanche danger ratings (for the next 3 days) is as a result of strong precipitation and winds forecasted for the region.
Tree well hazards will increase substantially this weekend as a result of the major amounts of snowfall expected for the region. Keep an eye on your riding group and ride in pairs.
This forecast brought to you by forecaster's Dave Kallai and Ryan Shelly
Past Weather
New snow, cold temperatures and some wind effect have made for outstanding snowmobiling and skiing/snowshoeing since the storm’s arrival several days ago. As a result of all the new snow, it appears that avalanche activity is occurring within the upper 20 cm to 50 cm of the upper snowpack. Expect this problem to increase as additional new snow arrives to the forecast area this weekend.
Weather Forecast
The next weather front is expected to arrive on Friday evening with strong to moderate winds. Expect the weather to become a bit more aggressive as strong winds and strong precipitation rates arrive Saturday, January 30th. Light precipitation for the East and North end of the forecast region while the West and South end of our bulletin area stand to receive substantial snowfall amounts.A strong Northwesterly flow will arrive on Friday evening. This frontal system will bring warm air and deliver strong southeast winds and precipitation rates.Saturday 20 cm Snow for the North island and 50 cm Snow for the South and mid-island, Moderate winds gusting to strong from the Southeast, Freezing level 750MSunday: (5 cm Snow North island) and (30 cm Snow South and mid-island), Moderate winds gusting to strong from the Southeast, Freezing level 850MMonday (5 cm Snow North island) and (10 cm Snow South and mid-island), Moderate winds from the Southeast, Freezing level 900M
Terrain Advice
Keep to simple terrain (terrain under 30 degrees slope angle) and utilize small slopes to test the reactivity of the recent snowfall.Keep an eye on snowfall rates, wind transport and rising temperatures for your area, as this promotes slab formation and “touchy/easily triggered” conditions.Be cautious when route-finding and transitioning from scoured areas into areas of wind loaded snow.Avoid open and steep slopes during periods of warming and rain. A small loose wet avalanche will entrain and gain enough mass to push a mountain traveller into gullies and over cliffs.Avoid travelling above or below cornices and keep to conservative decision-making.
Snowpack Summary
Over the week, 5-20 cm of snow fell and was transported by southeast winds creating soft slabs in the current affected areas. This overlies a sandwich of supportive melt-freeze crusts within the upper 60-80 cm of the upper snowpack. Below this, the snowpack is well settled.
Snowpack Details
- Surface: Wind distributed soft slab or low, dense snow on the crust.
- Upper: 20 to 50 cm below the surface exists a melt-freeze crust with facets (PWL) resting above this crust.
- Mid: Generally, well settled with several melt-freeze crust layers
- Lower: Well, settled and well bridged and includes a 10 cm thick layer of large facets
Problems
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.