Sporadic large avalanche activity continues to occur. See avalanche tab for info on reported large slide in Rae Glacier area. The November rain crust will remain a layer of concern for some time. JM
Confidence
Fair - Due to limited field observations
Weather Forecast
The NW flow will slowly change to a W and then a SW flow by Wednesday night. Light snow is expected to begin Wednesday night. Significant amounts of loose dry snow are available for wind transport so increasing winds may increase avalanche danger ratings in the Alpine as the week progresses.
Avalanche Summary
Report came into the office this afternoon of a size 2.0 avalanche in the Rae Glacier area and a larger avalanche, two to three days old in the same area. This larger avalanche was described as on a N aspect at 2600m with a fracture depth of 200cm. No other details are available at this time.
Snowpack Summary
The snowpack is settling. Some wind transport is still occurring at ridgetop. November rain crust continues to be a concern for step down potential of persistent slab above.
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.