Watch for isolated pockets of wind slab in the alpine. Though stability is improving, it remains possible to trigger avalanches on a recently buried weak layer.
Soft, isolated pockets of wind slab formed during a brief period of moderate wind on Monday. Wind slabs may be most easily triggered where they sit over a sun crust on solar aspects.
A layer of potentially weak crystals including facets, surface hoar and crust was buried at the end of February. As overlying snow gains slab property through settlement or wind effect, slab avalanches on this layer could become more likely.
Freezing levels drop to valley bottom for the forecast period as an arctic airmass overtakes the region.
Monday: Flurries bringing around 5 cm. Light to moderate northwest wind. Alpine temperature around -10 °C. Freezing level dropping to valley bottom.
Tuesday: Flurries bringing 5-10 cm. Light easterly wind. Alpine high around -12 °C.
Wednesday: Mostly sunny. Light easterly wind. Alpine temperatures around -15 °C.
Thursday: A mix of sun and cloud. Moderate northwest wind. Alpine temperatures around -8 °C.
Natural and explosive triggered cornices up to size 3 were reported on sunny Sunday.
Other solar induced natural activity over the weekend included loose dry up to size 1.5 and a size 2 storm slab.
Following a natural avalanche cycle up to size 2 during the storm earlier in the week, storm snow was touchy on Friday, with several rider triggered storm slab and loose dry avalanches around the region, including this remotely triggered size 1.5 near Golden.
Warm temperatures Thursday through Sunday are suspected to have sensitized buried weak layers such that explosive control work was able to trigger a few deep avalanches:
Surface snow has likely seen some redistribution by recent wind in the alpine. A few crusts may be found in and amongst the 30-60 cm of recent snow including a sun crust at the surface on solar aspects and an embedded melt freeze crust up to 1700 m on all aspects. The recent snow may also be sitting on an older sun crust on solar aspects, as well as weak surface hoar and faceted crystals on shaded aspects.
An interface from mid-February composed of sun crust and/or surface hoar is now 30-90 cm deep. Explosive work near Invermere (where it is 30-60 cm deep) on Sunday confirmed that this layer can still be triggered by large loads.
A layer of surface hoar from late January has not produced recent avalanche activity but crystals can still be identified 40-50 cm deep near Golden.
