The first bulletin for 2016! Happy New Year! If heading out tomorrow, watch for temperature changes and touchier windslabs than we're used to.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Sunny skies again tomorrow. We are expecting the warm air to arrive and bring the freezing level up to 2000m. The overnight low at 2500m -8 degrees. Given what we experienced today (-25 in the AM) that temperature might vary significantly. Tomorrow could have a rapid warming trend. The winds will be light at most elevations except for 2700m and above. Also of note is the weak inversion that is forecast.
Avalanche Summary
Forecasters witnessed a skier accidental today in alpine terrain. The feature was just below a pinch in a large alpine gully. The small slab avalanche triggered above the person and entrained a large amount of loose snow as it made its way downhill. Sz 2, 2700m, ran 400m vertical, SE aspect. There were also continuous loose dry avalanches pouring down high alpine gullies for most of the day. These were attributed to constant windloading and in some cases solar input.
Snowpack Summary
Last night's extended cold has removed most of the below treeline snowpack structure. In most places the ski penetration is 20-30cms with the occasional plunge to ground. On top of that, we have another layer of surface hoar growing up to 2500m. Old uptracks are still very supportive, but once off the beaten track, expect difficult trail breaking and much trickier skiing than what we've experienced so far this season. At treeline, the midpack is hanging in there and is more supportive. In many area, probing revealed a weak layer forming near the ground. The depth hoar is on its way! Once in the alpine, there is extensive wind affect in most areas. Sheltered areas still have good skiing on facets, while exposed areas have new windslabs mixed with weak facetted snow.
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 Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.