Regions
Northwest Coastal.
Spring Conditions. Expect the likelihood of wet slab and loose wet avalanches to increase during the heat of the day. Watch for clues like snowballing that the surface is heating up and the snowpack may be losing strength.
Weather Forecast
Clear overnight with freezing down to at least 1000 metres. Moderate southerly winds on Wednesday with clear skies and freezing levels up to 2500 metres. Mostly clear on Thursday with moderate southeast winds and cloud developing in the late afternoon. Freezing level up to 3000 metres on Thursday. Cloudy and cooler on Friday with freezing levels around 2000 metres and moderate to strong southeast winds.
Avalanche Summary
Numerous wet slab avalanches up to size 3.0 were reported from near Stewart in the 1400-1600 metre elevation band. Most of these avalanches were triggered by explosives and they were about 50 cm deep.
Snowpack Summary
Clearing and cooling overnight has re-frozen the upper snowpack down to about 700 metres. Previously, there was 20-40 mm of precipitation in the past few days. Most of this has fallen as rain up to about 1800 metres. Most of the precipitation has been in the near coastal ranges, with Stewart and Kitimat receiving closer to 40mm and areas around Terrace closer to 20mm. Winds have been strong out of the south; reports from Stewart of gusts above 100 km/hr on Monday that have developed wind slabs in the high alpine. Rain has soaked the snowpack at lower elevations. Some recent crusts within the upper snowpack may continue to provide a sliding layer for loose wet avalanches when forecast temperatures and freezing levels spike in the next few days.
Problems
Wet Slabs
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.