Recent strong northerly winds have created hard slabs on S-SW aspects. These sit atop a crust and are reactive to human triggering.
Weather Forecast
Mainly cloudy with isolated flurries today, alpine high of -12*C, and light SE ridge winds. More of the same tomorrow and Thursday, with sunny periods poking through the cloud and trace snowfall amounts. Alpine high of -12*C and light ridge winds. Friday may bring up to 10cm of snow, light to moderate ridge-top winds, and an alpine high of -9*C.
Snowpack Summary
Saturday's strong NE winds have created widespread wind slabs. These lay on a suncrust on S and W alpine aspects. Storm snow has been redistributed and is faceting due to the cold temps. Weak layers of concern, the Jan 31 and Jan 17 interfaces (surface hoar and sun crust), are down ~50cm and ~70cm at tree line.
Avalanche Summary
Natural activity has tapered off with alpine winds dying down. No avalanche activity observed yesterday in the highway corridor. No reports of human triggered avalanches yesterday after numerous reports from Saturday during an intense Northerly wind event.
Confidence
Due to the number of field observations
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.
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.