Solar triggered avalanches and cornice failures will increase in frequency the next few days as each day will be warmer than the previous. Temperatures expected to spike Wednesday and Thursday.
Weather Forecast
Tuesday will be sun and cloud, no snow, high of 3 C, light winds, and 2600m or higher freezing level. Wednesday will be similar but warmer and with a slightly higher freezing level. Thursday will be sunny and very warm with freezing level up to 3600m and 10 C temperatures.
Snowpack Summary
Sun or temperature crusts extend to treeline and into the alpine on southerly slopes. Persistent slabs can be found on most aspects at treeline and above. These have been reactive to large triggers like cornice failures. Below 1,900m the snowpack is going isothermal on a daily basis.
Avalanche Summary
Monday there was a report of a size 2 above upper weeping wall stopped at the trees. Another size 2 was noted on the Churchill slide path. Things are waking up with the rising temperatures. Sunday size 2 slab avalanche occurred on the E slopes of Lectern, initiating in the alpine and running to treeline. Loose wet activity is also increasing.
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.
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.