Avalanche Forecast

Fair

Synopsis: A weak and dirty ridge lingers over the Southern Columbias resulting in trace amounts of precipitation, partially cloudy skies and a nice melt freeze pattern for the forecast period.Thursday: Freezing Level: 1200m rising to 2100m; Precipitation: Trace; Wind: Treeline: Light, West | Ridgetop: Moderate, WFriday: Freezing Level: 1500m rising to 2000m; Precipitation: Trace; Wind: Treeline: Light, W | Ridgetop: Moderate, W/NWSaturday: Freezing Level: Valley Bottom rising to 1600m; Precipitation: 1:2mm - 1:3cm; Wind: Treeline: Light, NE | Ridgetop: Moderate, W/NW

A weak overnight refreeze Monday night and continued warm temperatures on Tuesday drove an avalanche cycle to size 2.5 on all aspects. Cornice fall in combination with ongoing wind transport at upper elevations initiated wind slab avalanches to size 2. Widespread pinwheels/roller-balls were observed in the southern portion of the region on all aspects between 1900m and 2600m.

Warm temperatures resulted in the freezing level reaching to almost 2500m early this week. This has helped to settle out last weeks storm snow, it's reported to be bonding well to the old surface. Strong winds out of both the SW and NW have redistributed what little dry snow still exists at upper elevations into wind slabs immediately lee of ridge crest.Three persistent weak layers exist in the highly variable snowpack of the South Columbia's:The mid-March sun crust/surface hoar layer down 50-80cm still has potential for human-triggering in isolated areas. The early-March crust/facet/surface hoar layer down around 80-120cm has become less susceptible to human triggering, but still has the capacity to produce large avalanches.The mid-February crust/facet/surface hoar combo is typically down 150 - 200cm. Direct triggering of this layer has become unlikely, however, cornice fall, a smaller avalanche in motion or prolonged warming could wake this layer up, which would result in very large and destructive avalanches.