Regions
South Coast Inland.
Expect hazard to be one step higher than forecast in localized areas that receive 30cm or more of new snow Tuesday night. Cautious route finding will be Critical to playing safe on Wednesday.
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Tuesday Night: 10-25cm of new snow / Moderate to strong southwesterly ridgetop winds / Freezing level around 1000m.Wednesday: 5-10 cm of new snow / Moderate southerly ridgetop winds / Freezing level around 1200m.Thursday: Mostly cloudy with flurries / Moderate southerly ridgetop winds / Freezing level dropping to around 800m.Friday: Mostly cloudy with isolated flurries / Light to moderate southwesterly ridgetop winds / Freezing level around 700m.
Avalanche Summary
On Monday, two explosive triggered size 3 storm slab avalanches were reported on north aspects between 2000-2300 m. in the Duffey Lake area. A natural size 3 storm slab avalanche also occurred in this area on Sunday. Looking forward, forecast snow and wind will promote ongoing storm slab avalanche activity, especially in higher elevation, lee terrain.
Snowpack Summary
By Tuesday morning the 72 hour snowfall totals were around 60cm in the Duffey/ Tenquille areas. Thanks to strong to extreme southwest winds, I would anticipate redistribution of the recent storm snow at all elevation bands with storm slabs lurking in lee and cross-loaded features. Further south in Coquihalla area, 72 hour storm totals were closer to 35 cm and winds were much lighter.50-120cm below the surface you'll likely find a few crusts that were buried during the first few weeks of January. Due to limited observations, not much is known about the current reactivity of these layers.The lower snowpack includes the mid-December crust layer. I'd expect an improving bond at this interface; however, the load of the new snow may tip the balance and reactivate this layer in isolated terrain - particularly in the north of the region where it's shown prolonged reactivity in snowpack tests.
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.