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 unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Northwest Inland.
Limited field observations and reports exist from this region. Conditions may be variable. It is important to be familiar with the snowpack and avalanche problems that may exist in your local mountains.
Confidence
Poor - Due to limited field observations for the entire period
Weather Forecast
A broad upper trough remains just offshore while a cooler, unstable onshore westerly flow has strengthened. A multitude of systems will bring light –moderate precipitation, and strong SW winds. The region returns to normal seasonal temperatures, as the arctic air retreats.Tuesday: Freezing levels near 500 m, snow amounts 10-20 cm, ridgetop winds SW 50-70 km/hr, alpine temps -10.Wednesday: Freezing levels near 500 m, snow amounts 2-5 cm, ridgetop winds W 30 km/hr, alpin temps -10.Thursday: Freezing levels at the surface, snow amounts 5-10 cm, ridgetop winds SW 20 km/hr, alpine temps -11.
Avalanche Summary
Recent reports of several loose, dry sluffs size 1.5 from steep, rocky terrain features running mid-path on Northerly aspects. For a bit more information in the Hankin Area, check out the Regional Forum Posts.
Snowpack Summary
Wind slab instabilities exist in the upper snowpack at treeline and in the alpine. They may be touchy to rider triggers; especially on leeward slopes and behind terrain features where pockets of wind slab easily build. At treeline depths in the southern part of the region range between 90-125 cm, but highly variable in the alpine with deep wind drifts and scoured slopes in exposed areas. Recent snowpack tests on a SE aspect around 1400m showed CTH (resistant "pop") on an old facet layer 55 cm down, and a rutschblock score of 5. Generally, the mid-pack is gaining strength and possibly even bridging the persistent weakness below.Digging down deeper is the early November facet/crust persistent layer. This crust sits near the base of the snowpack down 80-130 cm. Test results on this layer earlier this week produced hard results ("drops"). I have no current observations to suggest the snow above or below this interface is gaining strength, or weakening. In most areas, because this weakness is located near the ground, any associated avalanche activity will likely be limited to slopes with smooth ground cover.
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.