Regions
Northwest Coastal.
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Confidence
Fair - Due to the number of field observations
Weather Forecast
Mainly sunny and cool with some cloud later Monday. A series of weak storm systems will brush up against the coast and bring light snowfall amounts. Freezing levels near 600 m dropping to valley bottom by Wednesday. Outflow winds will persist.
Avalanche Summary
On Saturday explosive control triggered numerous storm slab avalanches size 2.5 at 1500 m on north aspects. A naturally triggered avalanche cycle was observed in response to last week's storm. At low elevations, many of these were wet and dug deep, failing to ground, up to size 2.5.
Snowpack Summary
Recent heavy rain affected southern parts of the region up to alpine elevations, while the far north remained drier and sports a weaker snowpack in general. Areas which previously received rain have probably now formed a hard frozen crust. High alpine and far northern areas are likely to have wind slabs and large fragile cornices. Deeper in the snowpack, weaknesses such as the mid-November crust-facet layer are still of concern to some operators.
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.