A touchy layer, with remote triggering potential means that you need to be aware of who is above and below you, minimize your exposure, and regroup in safe spots. Cautious terrain selection and good group management are essential.
Weather Forecast
Flurries are starting as a series of weather systems move into the region. Today expect trace of snow, with moderate SW winds and freezing levels rising to 1300m. Steady snow starts on Friday; we expect 25cm by the end of the day with freezing levels to 1600m and strong winds. Sat expect another 14cm, freezing levels at 1700m and moderate SW winds.
Snowpack Summary
A 60cm slab sits on the Jan 15 surface hoar. It will be deeper in lee features where loaded by south winds. The Jan 15 was widespread, largest at treeline, and on solar aspects sits on a sun crust. Tests indicate it is likely to be triggered (CTE SC) and propagate (PST 29/100 end). The Dec 17 surface hoar is down 100-150cm and stubbornly reactive.
Avalanche Summary
On Tuesday artillery control triggered over 30 size 2 to 3.5 avalanches from all aspects between 17-2700m. Notables were size 3.5's from the W face of Cheops and off Mt Tupper that ran into the creeks. Human triggered avalanches up to size 2.5 continue to occur in the region. Remote triggering from up to 300m has been reported.
Confidence
Timing of incoming weather systems is uncertain
Problems
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.
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.