Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Glacier.
Incremental snow squalls and strong winds overnight are re-loading start zones and lee slopes. The sensitivity to skier triggering is quite variable, so good snowpack and terrain evaluation are required.
Weather Forecast
The air mass will become colder and more unsettled throughout the day, with convective flurries, cloud and moderate winds. A ridge will build for later Friday, and the weekend is looking dryer and sunnier.
Snowpack Summary
An intense frontal system passed through last night with strong winds. We suspect significant loading occurred in start zones overnight, but the bond of storm snow is not yet known. North aspects will be most loaded, but solar aspects may be more reactive due to a buried suncrust-surface hoar combo , where wide propagations can be expected.
Avalanche Summary
A small avalanche cycle occurred yesterday, mostly from steep start zones on Mt. MacDonald. Explosive testing yesterday produced a size 1 avalanche on a north aspect. Two days ago, skiers on Mt. Sifton cut a cornice to check the slope, and released a size 2.5-3 avalanche on a south aspect. See photo: Connaught
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Friday
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.
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.
