A forecast uptick in southwest winds should sustain wind slab problems at high elevations. Stay aware of cornices that formed fragile new growth during the storm.
Wind slabs are most likely to be reactive in freshly wind loaded terrain features at upper elevations on Thursday. Forecast winds may add to this problem, forming small new slabs and obscuring recent ones.
Cornices are fragile due to rapid growth from recent snow and wind. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.
Wednesday night: Clear. Moderate to strong southwest winds increasing into the morning.
Thursday: A mix of sun and cloud with possible isolated flurries. Moderate to strong southwest winds. Alpine high temperatures around 0 with freezing levels to 2000 metres.
Friday: A mix of sun and cloud with isolated flurries. Light southwest winds. Alpine high temperatures around -1 with freezing levels to 1900 metres.
Saturday: Mainly sunny. Light southwest winds. Alpine high temperatures around +2 with freezing levels to 2200 metres.
On Monday, numerous skier and explosive triggered storm slab avalanches were reported size 1-1.5, largely on NW aspects. By Tuesday, storm slabs became more stubborn to explosives and results were limited. Observations in the Hellroaring area, which received less snow, include a few size 1 wind slabs and a cornice-triggered size 1.5.
Reports during the storm on Sunday include several natural storm slabs size 1-2 and a natural size 2 loose wet avalanche on a northeast aspect around 1700 m. It is suspected to have scrubbed down to a crust near the ground, as rain and warm temperatures destabilized the full depth of the snowpack.
New surface crusts have likely formed on solar aspects and below about 2000 metres. Forecast isolated flurries may add a skiff of dry snow to higher elevations while crusty surfaces below treeline become moist with daily rising freezing levels or light rain.
15-40 cm of recent snow has otherwise seen some redistribution by southwest to northwest wind, and seems to be bonding well with underlying surfaces.
A widespread crust layer from the mid-March warm spell can be found 30-60 cm deep, and small surface hoar has been observed at this depth on some isolated north-facing slopes. Reports suggest the snow is generally well bonded to these layers. Deeper layers are strong and have been unreactive over the past few weeks.
