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
THURSDAY: 5 cm (Duffy) to 20 cm (Coquihalla) by Thursday evening. Moderate SW winds. Warming with treeline temperatures a getting close to zero.FRIDAY: Another 20 cm possible (Coquihalla) but dry further north (Duffy). Moderate 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 1000 m and light southwesterly winds.
Avalanche Summary
No new avalanches have been reported since Monday, when only one slab avalanche reported: a size 2 on a South aspect in the alpine. Some loose dry sluffs reported from steep gullied terrain. Avalanche activity will increase with forecast snow, wind, and warming temperatures.
Snowpack Summary
Another 15-25 cm of fresh snow adds to the 10-35 cm of snow from the weekend that is bonding poorly to facets and buried surface hoar, as well as crust on previously sun-exposed slopes. Reports from the Duffy Lake area on Sunday include easy whumphing and cracking at ridge top. The widespread mid-February crust can be found down 40-80cm and seems to be well-bonded, although is reportedly weakening. 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
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.
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.