Warm temps and strong sw winds combined with new snow are creating ideal conditions for slab development. Heads up as you move into more wind affected areas. The times of "Given er" are at an end for a while...
Confidence
Moderate - Forecast snowfall amounts are uncertain on Friday
Weather Forecast
Warm temps and strong southwest winds are expected to continue overnight. Forecast models are currently calling for 7cm overnight and another 5cm of snow throughout the day on Friday. Freezing level on friday is forecast to be around 1900m.
Avalanche Summary
Forecaster were able to easily trigger a few smaller sz 1 avalanches on wind loaded features at TL in the Burstall Pass area. These slabs were failing down 20-30cm on the Jan 6th Infterface. A few sz 1.5 slabs were also observed along ridgelines on N and E aspects in Alpine areas that entrained the loose dry facets on the lower slopes running far.
Snowpack Summary
Up to 25cm of snow is now overlying the Jan 6th Facet/Surface hoar interface. Cracking was apparent in open wind affected terrain while travelling in treeline features today indicating that this layer is within the range of human triggerring. Where the snow is more wind affected triggerring will be easier. There was no cracking observed below treeline. Strong winds and warm temps are rapidly building new persistent slabs on this interface. Skiers will need to pay attention as the transition into open wind affected areas. Another 10cm of snow is expected to fall overnight under the influence of strong temps so its unlikely stability it likely to improve before the weekend.
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.