Rising winds are forcast to reach 70kph at ridge tops. This could cause rapid soft slab development. Use caution for soft wind slabs where slopes are exposed to the wind.
Weather Forecast
A large low in the gulf of Alaska is bringing cloudy and more stormy skies in from the South-West, flurries are forcast for today and tonight, and snow for Thursday. Amounts are predicted to be 2cm today, 5cm tonight, and 10 or more cm for thursday, but there is low confidence in the predicted amounts. Rising winds are forcast, SW 30 rising to S 70
Snowpack Summary
At treeline and above, soft windslabs have formed due to 30-50k winds at ridgelines. Elsewhere, 40cm of loose storm snow overlies a well settled snowpack. The Nov28 surface hoar is down about 80cm but only in some locations. The early Nov crust is widespread and down about 1.5m. Tests on these layers indicate they would be hard to trigger.
Avalanche Summary
Yesterday avalanches were observed up to size 2.5, and were dry slabs running to 1/4 fan.
Confidence
Intensity of incoming weather systems is uncertain
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.