Regions
Northwest Coastal.
Confidence
Fair - Due to variable weather conditions
Weather Forecast
A continued low over the Gulf of Alaska will whirl a series of convective systems through the southern part of the province, bringing light precipitation to the North West regions. Friday: Snow amounts 5-15 cm. Ridgetop winds light from the SW. Alpine temperatures near -4. Freezing levels 900 m then falling to valley bottom at night. Saturday/Sunday: The weekend will continue with quite the mixed bag of unsettled, spring-like convective weather. Expect bands of fast moving clouds, light precipitation, and periods of sun in the afternoons. Freezing levels 500- 800 m during the day, falling to valley bottom at night. Ridgetop winds will be light - moderate from the SE.
Avalanche Summary
On Wednesday numerous point releases, and wet slab avalanches were reported. These occurred on isolated steep south aspects, up to size 2.5 below treeline elevations. Natural glide crack, slab releases also occurred below treeline up to size 3. Avalanche control with the use of explosives triggered several size 2-3 glide slabs, below 1000 m. The snowpack below treeline will remain unstable until the region receives a good re-freeze. Unsettled weather conditions are forecast. It's important to pay attention to weather, and it's influence on the snowpack when recreating in your local mountains. I suspect the period will be fairly cloudy, but if periods of sun shine through, beware of solar aspects.
Snowpack Summary
Moderate to strong southeast winds have created wind slabs on opposite slopes and terrain features in the alpine, and treeline. Spring-like conditions have existed over the past several days forming crusts on solar aspects at all elevations that become moist under sunny skies during the day. Melt conditions exist on all aspects below 1000 m, with no significant re-freeze. This has developed a well settled upper snowpack with no significant layers of concern. New surface hoar growth up to 10 mm has been reported on sheltered North aspects. Forecast snow may initially have a poor bond to these new surface forms (crusts, surface hoar). Below all this, down 60-120 cm exists a very spotty surface hoar/ facet interface. Operations from the field noted no recent activity on this layer. I suspect it's becoming dormant, but would be suspicious of large triggers like cornice fall, or under the weight of a sled and it's rider in specific areas. Cornices in the region are reported to be very large and potentially unstable.
Problems
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.
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.
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.