The Pacific storm is bringing heavy snowfall between this morning and Thursday evening. Limit exposure to overhead avalanche hazard. Make conservative terrain choices!
Weather Forecast
A winter storm is upon us and is forecast to bring us 40cm+ of snow by the end of the day Thursday. The main pulse should occur Wednesday night into Thursday morning. Moderate to strong SW winds and rising freezing level to 1500m will prime the surface layers with wind and storm slab formation.
Snowpack Summary
A winter storm is potentially bring us 40cm+ snow by Thursday evening. Previous strong S'ly winds created wind slabs in the alpine and exposed areas at TL. These slabs are now buried under fresh storm slab formations. Recent observations showed failures at these interfaces, with potential to step down to our plethora of persistent weak layers.
Avalanche Summary
Several naturals in the HWY corridor Monday up to size 3. Only three new slides observed in the corridor Tuesday. On McGill Shoulder Monday there was a skier accidental size 2, 30-50cm deep, 50m wide and ran for 300m in length. Significant sluffing was also observed in the Bostock drainage.
Confidence
Forecast snowfall amounts are uncertain
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.