The best skiing and riding conditions exist at and below tree line in sheltered locations. This is also where the January 17th Surface Hoar layer loiters.
Weather Forecast
A mild inversion will settle in at higher elevations today, accompanied by clear skies and light winds, with a high of -8 in the alpine. Clouds will start to roll in this afternoon, flurries overnight and up to 10cm of new snow for Friday. Saturday may give us another 5cm, before the Arctic High-Pressure moves back South over Rogers Pass.
Snowpack Summary
A dusting of new snow covers old hard wind slabs, and scoured surfaces in the ALP and exposed areas of TL. Cold temperatures continue to promote near surface facetting at all elevations; deteriorating the bonds of the upper snowpack. Wind slabs were most active on solar asp, where crusts are buried. The Jan 17 SH is down 50-70cm at TL and below.
Avalanche Summary
Yesterday we observed two small sz 1.5 wind slabs on north aspects in "extreme terrain", in the alpine. On Saturday there was a natural cycle triggered by strong N-NE winds. Since the weekend we have only seen sporadic small wind slabs up to size 1.5 in the alpine. There have been no reports of any new avalanches on the Jan17th PWL in over a week.
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.