Sunshine and warming are set to maintain heightened avalanche danger over the coming days. Expect stability to deteriorate as each day progresses.
Summary
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Wednesday: Mainly cloudy with isolated flurries and a trace of new snow. Light southwest winds. Freezing level rising to 1700 metres with alpine high temperatures around -6.Thursday: Mainly cloudy. Light to moderate south winds. Freezing level rising to 1900 metres with alpine high temperatures around -3. Weak overnight cooling.Friday: Cloudy with flurries beginning in the evening and continuing overnight. Moderate south winds. Freezing level to 1900 metres with alpine high temperatures around -2.
Avalanche Summary
On Sunday there was a report of a natural, cornice-triggered size 2.5 persistent slab avalanche on a west aspect at 2350 m that is believed to have failed on the mid-March layer.Friday there was a report of a natural cornice collapse that produced a size 3 deep persistent slab avalanche that failed on an early-season layer (300 cm deep) on a northeast aspect at 2600 m. Several loose, wet releases up to size 2.5, running to ground in low elevation paths were also reported on Friday.Wednesday there was a report of natural cornice failure that resulted in a size 2.5 wind slab release on a northeast aspect at 2700 m, while a skier was able to trigger a size 2 wind slab (40 cm deep and 100 m wide) on a recently buried crust on a similar aspect at 2400 m. Last Tuesday, another natural size 2.5 cornice failure was reported on a north facing alpine feature.
Snowpack Summary
About 30 cm of recent snow covers a supportive crust on all aspects to at least 2100 m (and possibly higher on south aspects), while 40-60 cm of storm snow can be found at higher elevations. Below 2200 m this new snow has a surface crust becoming moist or wet by the afternoon.Within the upper snowpack there are now several different crusts with only the shallowest of these remaining a concern as the uppermost layer of storm snow settles and bonds to it.There is some lingering concern around the mid-March persistent weak Layer in the alpine where it is found 100 to 150 cm below the surface. This buried crust/surface hoar interface is still capable of producing large avalanches if it is triggered (think step-down from a surface avalanche or a cornice collapse).Deeper persistent weak layers from December and January may be starting to become reactive to very large triggers. A recent cornice collapse is believe to have initiated a slab release on an early season layer, 300 cm deep.
cgarritty,
Avalanche Canada
