Warm spring daytime temperatures are here - watch for surface snow turning wet and be wary of cornices and overhead hazards.
On sheltered, polar aspects at higher elevations cold, dry snow prevails. With forecast increased wind and light flurries, watch for reactive slabs where dry snow is redistributed.
The snowpack is slowly recovering and cooling from the recent sun and warm temperatures. A weak pulse could drop up to 10 mm wet precipitation, this load could further destabilize an already dynamic snowpack prolonging the wet avalanche hazard.
Wet-loose avalanches to size 2 were reported on Saturday occurring in solar aspects. Cornice failures were also reported, but none triggered slabs on the slopes below.
On Friday, several wet loose avalanches occurred on solar slopes. A few storm slab avalanches were reported (likely solar-induced or where warm temperatures encouraged the snow to settle and bond), the most impressive was a natural size 2.5 slab avalanche on SW terrain around 1800 m in the Brandywine area. A few large cornice failures were also reported, most did not trigger any slabs on the slopes below, however, large cornices are still proving reactive and the size 1.5-2.5 cornice chucks and entrained debris could still be very hazardous to a rider.
On Thursday, reactive wind slabs were reported around Whistler-Blackcomb including a size 1.5 in the Poop Chutes and a size 1.5 in S Turn (Wayne Flann Blog).
On Wednesday, skiers triggered a size 1 storm slab on a convex rollover with a crown 10-30 cm deep near Rainbow Mountain. Additionally, a few natural wind slabs were reported up to size 1 and explosive control produced several cornice falls up to size 2.5 and wind slabs to size 1.
In the northernmost end of the forecast region (near the Homathko Icefield), skiers found a reactive layer of surface hoar buried 65 cm deep below the recent storm snow, and observed natural avalanches to size 3.
On Tuesday, a few human-triggered storm and wind slab avalanches were reported up to size 2. Natural cornice failures and dry loose avalanches were also seen to size 1.
Daytime warming or wet flurries will promote moist snow surfaces, continuing to destabilize the upper snowpack. Cornices loom over ridgelines and may become weak during periods of solar radiation or warming.
A sun crust has formed on all aspects up to 1800 m and solar aspects into the alpine. At higher elevations, up to 40 cm of recent storm snow is settling and bonding an old crust on solars and faceted snow on polar aspects. Recent southwest wind pressed surfaces and formed slabs on lee slopes at exposed treeline and into the alpine.
Deeper in the mid-pack, down 90-200cm, a couple of layers of facets-crusts are found at treeline and higher. The remainder of the mid and lower snowpack is well-settled and strong.
Sunday night
Starry sky with increasing clouds. Southeast wind gusting to 20 km/hr. Treeline low temperature -4 C. Freezing level 1200 m.
Monday
Flurries start early Monday, trace to 10 mm at higher elevations through the day. Southeast wind 10-20 km/hr. Treeline high temperature +1 C. Freezing level 1500 m.
TuesdayTapering flurries transitioning to sunny skies. Light northeast wind. Treeline high temperature +1 C. Freezing level 1500 m.
WednesdaySunny with patchy clouds. Light southwest wind. Treeline high temperature +1 C. Freezing level 1200 m.
More details can be found in the Mountain Weather Forecast.
