Warmth remains the primary driver of avalanche hazard as we shift into a more spring like pattern. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.
Weather Forecast
MONDAY: Freezing level starting at valley bottom, rising to 1500m. Light variable winds at all elevations. No significant precipitation expected. Mostly clear skies.TUESDAY: Freezing level starting at valley bottom, rising to 1700m. Light SW winds at all elevations. No significant precipitation expected. Mostly clear skies.WEDNESDAY: Freezing level starting at 1200m, rising to 2100m. Light W/NW winds at all elevations. No significant precipitation expected. Clear skies.
Avalanche Summary
No new avalanche activity reported from Saturday. In the days leading up to the weekend a handful of large avalanches were reported, most were from north aspects, with the odd event on other aspects. A number of cornice failures were also observed.
Snowpack Summary
Recent squally snow showers have brought 15-30 cm of snow, which has been shifted into wind slabs. This new snow sits above a crust which varies in thickness with elevation. Cornices are large and vulnerable. Two crust/facet interfaces, formed in March and February, sit about 80-120 cm deep in the snowpack. These weaknesses are becoming more stubborn to trigger, but still react in snowpack tests indicating they still have the potential for wide propagation resulting in very large avalanches if triggered. Basal facets are currently dormant but may wake up with sustained warm temperatures.
Problems
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.
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.
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.