Regions
South Coast Inland.
We're moving into a period of HIGH danger with rapid loading of the snowpack on Wednesday and Thursday: rain to treeline and heavy snow in the alpine.
Confidence
Low - Intensity of incoming weather systems is uncertain
Weather Forecast
Warm and wet on Wednesday - Thursday. Cooling with light preciptation on Friday. WEDNESDAY: Rain to treeline (30-50mm) ; wet heavy snow in the alpine (30-50cm) / Strong southerly winds becoming moderate / Freezing level around 2300m / High temperatures to +3 Celsius. THURSDAY: Wet snow (20-30cm Coquihalla ; 30-50cm Duffey Lake road) / Moderate southeasterly winds / Freezing level around 1300 m. FRIDAY: Mostly cloudy with isolated flurries / High temperatures to +1 Celsius / Light-moderate southerly winds / Freezing level around 1100 m.
Avalanche Summary
On Monday there were several loose wet avalanches to Size 2 on solar (southerly) aspects, and some moist slabs to size 1.5 as well.
Snowpack Summary
The recent warming and sunny conditions gave us a widespread sun crust on all but high northerly (and some westerly) aspects, where there is still some cold snow to be found. Last week we had 60-80cm storm snow (lower amounts in the north), which fell with moderate to strong southwest winds.The main concern in the Duffey zone is lingering storm and wind slabs, which have given moderate resistant and sudden results (down 30-40cm and also 60-70cm) in snowpack tests (see above for more information). On the Coquihalla, a temperature crust can be found up to 1800m and significant wind effect occurred at upper treeline and alpine elevations.The mid-December facets down 130-160 cm still remain a concern especially in shallower snowpack areas in the Duffey, Hurley and/ or South Chilcotins. These deeper weaknesses warrant monitoring, especially with rapid warming next week. In southern areas (Coquihalla), the lower snowpack is reportedly well settled (stronger), than it is to the north.
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.
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.
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.