Regions
Kootenay Boundary.
Incremental loading is expected to reach the tipping point as forecast new snow and wind add to the load of storm snow.
Confidence
Fair - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Overnight and Monday: 10-15 cm of snow above 1000 metres overnight with strong Southwest winds. Another 10-15 cm during the day combined with moderate Southwest winds and freezing levels rising to about 1500 metres.Tuesday: Snow ending overnight and a chance of broken skies during the day. Light Southwest winds building during the day to strong by evening as the next pulse of moisture moves quickly into the region.Wednesday: Snow ending by early morning. Winds becoming light Southwest with high cloud and some sunny breaks.
Avalanche Summary
Explosive control produced many size 2.0 avalanches in the storm snow. Forecast new snow and very strong winds are expected to add to the load above the buried weak layers. Human triggering is expected to continue, and natural avalanches may result from the new storm loading.
Snowpack Summary
40-50 cm of recent storm snow has been transported into deep pockets of wind slab on North thru East aspects. Below the storm snow there is about 20 cm of snow from last week that buried the late January layer of crusts and/or facets and surface hoar. This persistent weak layer from Late January continues to be the sliding layer for natural and human triggered avalanches. The mid snowpack is well settled and strong. The deeply buried weak layers of early season facets and depth hoar have been dormant, but they may become reactive with the right combination of added load and warm temperatures. The forecast new snow and wind are expected to add to the load above the late January weak layer, and may result in avalanches running naturally or increased sensitivity to human triggers at this interface.
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.