The persistent layers that plagued the northern regions is becoming more of a concern here recently. Forecasters triggered a large avalanche involving the Jan 6th today. Avoid thin snowpack areas in big terrain right now.
Weather Forecast
The winds will be a very important component over the next 48hrs. Tonight they are expected to pick up and hit 55km/hr at 2500m. Tomorrow they will be steady at 50km/hr with gusts up to 90. They will be steady out of the west for the next while. Isolated flurries will bring only a few cm's close to the divide. The alpine high will be -4 tomorrow. The freezing level will creep up to 1800m.
Avalanche Summary
Forecasters had a near miss today and kicked off a sz2.5. It was on a moraine feature (Murray Moraines area) that drops into more shallow terrain. The avalanche propagated almost 100m and was up to 80cm deep. The Jan 6th was the failure plane and the start elevation was 2300m. Aside from that, there were also some small loosed dry avalanches noted as well as cracking and whumphing(within the storm snow) in shallow areas(Aster Lake region).
Snowpack Summary
Last night saw 5-10cm's of new snow throughout the region. Close to the divide seemed to get the most with 11cm. The winds that accompanied the snow were slightly less than expected, but still enough to create fresh windslabs at upper treeline and alpine. Including this snow, there is now 15-20cm of recent snow on top of the Feb 27th interface. The Feb 27th interface consists of a crust on south aspects, and a density change on polar aspects and the alpine. The bond with this layer is questionable, and in areas with a stiffer slab may be suspect. The Feb 11th layer is similar in many ways, variable with a suspect bond and aspect/elevation dependant. It is down 40cm's. The Jan 6th layer appears to be waking up in places. Especially in thin areas at treeline and alpine elevations. It is down 60-90cm's at treeline/upper treeline and is becoming more reactive with the additional load.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.