Wind slabs may remain sensitive to triggering Sunday. The sun can pack a punch at this time of year and the new snow will be particularly sensitive to it. Be ready to back off sunny slopes before the snow surface is moist or wet.
Recent snow and wind have formed wind slabs in immediate lees of ridge crests and roll-overs at upper elevations. They may remain sensitive to triggering Sunday.
Cornices are especially fragile this time of year, especially when the sun is out. Cornice falls are dangerous on their own and they can also trigger slabs on slopes below.
A ridge of high pressure sets up over the province. Freezing levels are forecast to steadily rise through the week.
Saturday night: Clearing. Wind easing to light northwest. Alpine temperature around -12. Freezing level valley bottom.
Sunday: Mix of sun and cloud. Light northwest wind. Alpine temperature around -8. Freezing level 1300 m.
Monday: Sunny. Light to moderate northeast wind. Alpine temperature around -6. Freezing level 1500 m.
Tuesday: Sunny. Light to moderate northeast wind. Alpine temperature around -4. Freezing level 1800 m.
Wind slabs have shown quite limited reactivity in the last couple of days, a few natural and ski cut size 1-1.5 were observed on Saturday. On Friday, most activity in the recent snow has been limited to size 1 loose snow avalanches. One size 2 was reported.
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.
20-30 cm of recent snow may have formed pockets of wind slab on leeward slopes and behind terrain features. 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.
