Regions
Northwest Inland.
New storm snow, strong winds, and rising temperatures are increasing the avalanche danger.
Confidence
Poor - Due to the number of field observations
Weather Forecast
Tonight and Saturday: Very strong Westerly winds tonight becoming very strong Southwest by morning. Expect 10-15 cms of snow above about 900 metres elevation overnight and another 10-20 cms during the day. Warm Pacific moisture is forecast to push Eastward, driving out any remaining arctic air.Sunday:Models do not agree on how much Pacific moisture will continue to push into the Inland region. The range is 5-20 cms, I am expecting closer to 5 cms. Expect strong Southwesterly winds, cooling temperatures and dropping freezing levels. Monday:Winds becoming more Westerly. Freezing levels continue to drop and light flurries continue.
Avalanche Summary
New storm snow is expected to increase the avalanche danger. The weak shallow snowpack may not support the added load of new storm snow. Strong winds, new snow, and rising temperatures are expected to increase the sensitivity to triggering by skiers and sledders.
Snowpack Summary
Rising freezing levels and warm temperatures are settling the new snow into a cohesive slab above the recently buried weak surface layers. The snowpack is generally shallow across the region and in some areas is below the recorded minimum values. New snow is expected to develop a storm slab at higher elevations. Very strong winds are transporting snow into deep pockets of stiff slabby snow. Cold temperatures at the beginning of December created near surface facetted snow and surface hoar above old wind crusts. The new warmer storm snow is not expected to bond well to these old buried layers. Expect a lot of variation in snow depths across the region, with areas in the Southwest likely to be more like the Northwest Coastal region.
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.