Regions
Kootenay Boundary.
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Weather Forecast
Heavy snowfall is expected overnight (Monday night) with 30 + cm expected in some areas by morning. Strong to extreme SW winds, freezing levels around 1100 m. On Tuesday, Heavy snowfall is expected to continue into Tuesday and become lighter in the afternoon. Winds should start to diminish. Freezing levels should fall slightly. On Wednesday, there may be a lull between storms, although snowfall is expected to start up again later on in the day. On Thursday, another frontal system arrives in this region, bringing further heavy snowfall, strong SW winds and freezing levels in the 1200 m range.
Avalanche Summary
On Sunday, avalanches could be easily triggered in the new storm snow up to size 1.5. Sluggish sluffing in the storm snow was observed in steep terrain on Saturday.From earlier in the week:Several natural avalanches were reported Thursday to size 3. One noteworthy event was a size 2 avalanche that was triggered by cornice fall. The size 2 ran 50m before triggering a size 3 avalanche in lower angle terrain. The crown was reported to be 200cm in depth, failing on the Feb. 08 SH. One reported avalanche was remote triggered from 20m away on a 35 degree slope.
Snowpack Summary
Approximately 25 cm new snow fell on top of previous storm amounts from Friday night and Saturday night. This has added to the snow amounts overlying a 2 - 6mm surface hoar on north aspects and a 2cm sun crust on solar aspects. Moist snow was found Friday to 1800m, I suspect there was little change Saturday. The leap year SH is now down around 40 - 50 cm and is failing as a resistant planar shear in snowpack tests. The early February surface hoar is down 80 - 140cm, snowpack tests show moderate to hard forces generating sudden planar shears on this layer.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.
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.