Regions
Northwest Coastal.
A warm, wet and windy storm is expect increase danger and result in natural avalanche activity.
Confidence
Fair - Due to the number of field observations
Weather Forecast
On Tuesday freezing levels are expected to rise as high as 1800 m while a Pacific frontal system brings another 20-40 mm of precipitation and strong southwesterly alpine winds. Wednesday is looking slightly drier and cooler with 5-10 mm of precipitation and freezing levels around 1500 m as the alpine winds shift to moderate southeasterlies. At this point, Thursday is looking totally dry as freezing levels drop down to 1300 m and winds ease off.
Avalanche Summary
No new avalanches were reported. A couple fresh natural wind slab avalanches were reported from an area northeast of Stewart on Friday. These slides were observed on west facing slopes near treeline, and were an average of 20 cm deep. Similar activity is possible throughout the region.
Snowpack Summary
Conditions vary significantly throughout the region. In general, the snowpack is shallow, facetted, and wind affected. Approximately 5-15 cm of recent warm storm snow sits on a mix of surface hoar or faceted snow in sheltered areas, and wind slab or ice crusts in exposed terrain. Strong NE-SE winds have created dense new wind slabs in alpine and exposed treeline areas on the leeward side of ridge crests and terrain features. The mid-November crust-facet layer is now 40-60 cm deep and recently gave easy to moderate shears in snowpack tests.
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.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.