Recently formed wind slabs may remain sensitive to triggering Saturday. The new snow will be prone to solar-triggered loose dry sluffing if the sun comes out.
Cornices and glide slabs are best managed by staying well away from them.
New snow and strong southwest to northwest wind will likely form fresh and reactive wind slabs in immediate lees of ridgecrests and roll-overs at upper elevations.
The unsettled weather begins to clear up over the weekend as a ridge of high pressure sets up over the province.
Friday Night: 5-10 cm new snow. Strong southwest winds at ridgetop. Alpine temperature near -7. Freezing level 1000 m.
Saturday: A mix of sun and cloud with convective flurries up to 5 cm. Ridgetop wind light to moderate from the northwest. Alpine temperatures near -10. Freezing level 1000 m.
Sunday: Sunny. Light northwest wind. Alpine temperature near -5. Freezing level 1500 m.
Monday: Sunny. Light northeast wind. Alpine temperature near -4. Freezing level 1700 m.
Most activity in the recent snow has been limited to loose dry sluffing. Wind slabs have shown quite limited reactivity in the last couple of days, the odd ski cut producing size 1-1.5. On Wednesday, a large size 3.5 wind slab was reported from a North aspect around 2400 m in the Glacier Park region.
A couple of natural cornice failures size 2.5 observed Thursday did not trigger slabs on slopes below.
Neighboring Glacier National Park reported a few very large (size 3-4) glide slab releases on Thursday. Glide slabs are hard to predict and can release at any time so it is important to avoid slopes with glide cracks.
On Tuesday, a natural size 3.5 wet slab was reported from an S-SW aspect at 2500 m to 1800 m along with numerous wet loose avalanches up to size 1. We can expect more activity like this in the heat next week.
15-25 cm of new snow over the past few days has been wind affected in exposed alpine terrain, forming wind slabs in immediate lees of ridgetops. On North aspects in the alpine, the recent snow sits on dry wintery snow surfaces and possibly surface hoar on wind-sheltered slopes. Elsewhere, it sits on a series of melt-freeze crusts on all aspects below 1900 m and southerly aspects to mountain top. Reports indicate snow is bonding well at these interfaces.
The recent warm weather is expected to have helped old persistent weak layers heal, including a few crusts buried over the last month as well as a facet layer 150 cm deep from the mid-February cold snap.
