Regions
South Coast Inland.
Snowfall amounts may vary throughout the region. In the Cascasdes, heavy snow is expected to result in HIGH danger, while further north, much drier conditions are expected to result in slightly lower danger.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
FRIDAY: Another 20 cm possible (Coquihalla) but dry further north (Duffy). Strong SW winds. Temperatures starting to cool a few degrees.SATURDAY: A mix of sun and cloud with scattered flurries bring as much as 5-10 cm to some areas. Freezing levels around 700 m and light southwesterly winds.SUNDAY: A mix of sun and cloud with scattered flurries bring as much as 5-10 cm to some areas. Freezing levels around 00 m and light southerly winds.
Avalanche Summary
Reports from Wednesday include several natural avalanched in steep leeward alpine terrain up to Size 2. Avalanche activity will increase with forecast snow, wind, and warming temperatures.
Snowpack Summary
Much of the region received 30-50cm of fresh snow since the weekend, which has been blown into deep drifts by southerly winds and is bonding poorly to facets and buried surface hoar, as well as crust on previously sun-exposed slopes. The widespread mid-February crust is below all this. In the northern part of the region, a facet/surface hoar weakness buried early February, is now down around a metre and remains reactive in snowpack tests. It is also suspected as the failure plane in at least one of two recent large persistent slab avalanches in the Hurley Pass area. In the Cascades (e.g. Coquihalla), the mid and lower snowpack are well settled and strong. Forecast new snow is likely to arrive with strong SW winds and warming temperatures.
Problems
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.