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 residual dribs and drabs of those systems to the northern regions. Friday: Snow amounts 5-10 cm. Ridgetop winds light from the SW. Alpine temperatures near -4. Freezing levels 1200m. 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 look to behave at 1000-1100 m during the day, then falling to valley bottom at night.
Avalanche Summary
Natural avalanche activity seems to have tapered off over the past couple days. Most recent reports are of loose wet slabs (unknown size) below 1400 m. I suspect weather limited most operations from the field.Earlier this week the region saw many large cornice falls on N-E slopes. These did trigger smaller size 1-2 avalanches, but nothing stepped down to the deep persistent layer. This is good. Yet I wouldn't' rule out the potential, as we saw that layer reactive only 6 days ago. Numerous loose wet avalanches were also reported on Monday on various aspects, running up to size 2.
Snowpack Summary
Recently formed, variable wind slabs exist in the alpine, treeline, and open areas below treeline. These can be found on lee slopes, and behind terrain features. Over the past several days, spring-like conditions have influenced the snowpack. Solar radiation has led to moist surfaces on sunny slopes up to ridgetop during the day, and other aspects moist below 1500 m with limited crust recovery overnight. Cornices have grown large and may become unstable under sunny skies; they may act as a large trigger on slopes below. A well settled, consolidated slab overlies a persistent weak layer that was buried in early February. Now 1-2 m below the surface, these weaknesses include surface hoar, facets or crusts. Concern still exists potentially for deep and destructive releases at this interface. This may be a low probability, high consequence problem that may require a large trigger.
Problems
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.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.