Regions
Kootenay Boundary.
Confidence
Fair - Intensity of incoming weather is uncertain on Tuesday
Weather Forecast
A trough of low pressure anchored over SW BC allows for moist SW flow for the forecast period. Snowfall picks up again around 10 pm Sunday night; the KB is expected to pick up 5 cm overnight. MONDAY: Monday morning should be cool & crisp with freezing levels at valley bottom, but the cold won't last long, freezing levels climb to 1500 m before lunch as snow fall begins. 5 - 10 cm's are expected during the day with strong SW winds at ridge top & a more moderate southerly at treeline. Remnants of a deep pacific low slide through the region Monday afternoon/evening bringing ridge top winds up to extreme. 10 - 20 cm of snow are expected Monday evening. TUESDAY: SW winds in excess of 100 km/h at ridge top persist through most of Tuesday. Another 10 - 20 cm are expected Tuesday with intensities tapering Tuesday afternoon. SW winds in excess of 100 km/h at ridge top persist through most of Tuesday. WEDNESDAY: A brief ridge of high pressure is in place Wednesday morning, but, the current models show another significant system moving into the region Wednesday afternoon.
Avalanche Summary
Low level cloud made for poor visibility Saturday, as a result, there isn't much to report in the way of avalanche activity. Sluggish sluffing in the storm snow was observed in steep terrain on Saturday though.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
Kootenay pass picked up 12 cm of rather wet snow Saturday night, but the rest of the region is reporting only a few cm's. This snow adds to a few cm that fell Friday night, all of which rests on 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.