This is the last avalanche bulletin with danger ratings for this region this season.
Confidence
Poor - Due to the number of field observations
Weather Forecast
Mostly clear overnight with light winds and freezing levels remaining above 2400 metres. Mostly sunny with light winds and freezing levels rising up to about 3000 metres on Monday. Alpine temperatures are expected to be around +10 celcius. The ridge of high pressure is expected to break down sometime Tuesday allowing a weak system to move onto the south coast.
Avalanche Summary
On Saturday the overnight crust held up for most of the day resulting in only small loose wet avalanches and pin-wheeling. On Friday, numerous solar triggered natural loose wet avalanches up to size 2 were reported. One natural wet slab size 1.5 was reported that ran to the top of the run-out zone. A natural cornice failure size 1 also occurred and did not pull a slab from the slope below. With warming and periods of intense solar radiation avalanche danger will rise, solar triggered slab avalanches, failing cornices and loose wet avalanches will likely continue. Be aware of rapidly changing conditions.
Snowpack Summary
Upper elevations have received 25-40 cm of recent storm snow. The new snow sits on the April 10th persistent weak interface including crusts, facets and spotty surface hoar on high, northerly aspects. This interface has shown a poor bond and has been reactive naturally and to human triggers. Moderate to strong south west winds have redistributed the recent storm snow into wind slabs on leeward slopes and behind terrain features. The mid-March pwl is down 100-150 cm and has been producing hard, resistant results in snowpack tests and has been dormant. There is a low probability of triggering this layer, however; if it is triggered the consequence would be high. Large looming cornices may become weak with solar radiation and daytime warming. If a cornice fails it could trigger a large avalanche from the slope below.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.