Wind and snow have built fresh wind slabs. Avoid lingering in the runout of avalanche paths as cornice fall could trigger a large avalanche, especially if the sun comes out in full force.
Summary
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
We're looking at snow on Wednesday, isolated flurries through Thursday, and a clear sunny day on Friday. WEDNESDAY: Snow Tuesday overnight to Wednesday (5-15cm) and moderate south wind, freezing levels 1900m, alpine temperature around -1 C.THURSDAY: Isolated flurries (5cm possible). Moderate southwest wind, freezing level around 1800 m with alpine temperature around -1 C.FRIDAY: Mainly sunny. Moderate southwest wind, freezing levels 1700m.
Avalanche Summary
On Tuesday, cornice fall triggered a Size 2 soft slab near Fernie on an east facing aspect near 2000m.On Monday, three natural storm slab avalanches Sized 1.5-2.5 were reported on northeast aspects between 1600 - 1800m near Fernie. Average depths were 20-35cm.On Sunday, explosives control work yielded a pair of Size 2 storm slabs (25-50cm thick) running on southeast aspects near 2000m elevation near Fernie. The Moccasin glide crack slid sometime Saturday night, running to ground.
See here for photo and more info.Expect wind slabs to develop as winds continue to transport snow at treeline and in the alpine. Be aware of overhead hazard and the possibility of avalanches running to valley bottom, especially of the sun comes out causing large cornices to fall.
See here for more information. Looking ahead, a significant concern is the potential for large deep persistent slab avalanches triggered by natural triggers such as a cornice fall. See the forecaster blog for advice on managing avalanches that are not likely, but if they are triggered, are almost unsurvivable. See (
here) for details.
Snowpack Summary
Warm temperatures on Monday (up to +4 Celsius at treeline) has left a 1-2cm thick breakable crust at most elevations, capped with a few centimeters of light snow. The storm on Friday-Saturday had some intense convective activity which brought locally heavy snowfall (or graupel) and storm totals of 20-45cm by Monday. Winds at times were moderate (south) westerly at ridge top with lots of transport. Recent snowpack tests have shown some reactivity in the storm snow layer (down 20-30cms) and also on the March 21st crust (down 40-60cm, giving propagation-likely test results). In some locations the recent snow is propagating and peeling off the March 21st crust with the additional loading (see Avalanche Summary above). Below 1600m (or on slopes facing the sun) the snow surface typically becomes moist in the afternoon with daytime heating / solar input. Depending on cloud cover, a (breakable) crust forms overnight. Isolated basal facets exist in shallow snowpack areas and still have the potential to produce destructive full-depth avalanches.
mgrist,
Avalanche Canada
