Regions
Northwest Coastal.
Confidence
Poor - Freezing levels are uncertain
Weather Forecast
Friday: Clouds and a few cm of snow, falling as rain below treeline. Freezing level around 1200 m. Light northerly winds.Saturday: Mainly cloudy, with sunny breaks. Some lingering light precipitation is possible in the morning, becoming dry by afternoon . Light, variable winds. Freezing level around 1200 m.Sunday: Mainly cloudy. Freezing level near 1500 m. Light winds, increasing from the SW by evening as a low pressure system approaches.
Avalanche Summary
Several natural glide avalanches were reported this week on E to SW aspects below treeline, in the size 2-3.5 range. Wet loose avalanches up to size 2.5 were also observed in response to warming and sunshine. Last week, a large icefall triggered a slab in the Bear Pass area, creating a size 4 avalanche.
Snowpack Summary
Glide cracks have opened up and pose the threat of large, full-depth releases, especially on steep rocky terrain features at low elevations. Otherwise, a relatively strong and deep spring snowpack exists, which becomes weak during periods of warm weather or rainfall. Recently, a lack of overnight freezing below about 1500m has left the snowpack weak. Large cornices and ice cliffs pose a threat from above. Pockets of dry snow and surface hoar may still be found on high north aspects. Areas of wind slab may exist near ridge crests.
Problems
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.