The avalanche danger is moving into the extreme ranger over the next few days. With limited overnight freezing forecasted, anticipate the danger to remain in the high range into the late evening.
Weather Forecast
Very warm temperatures are forecasted with freezing levels extending high into the alpine, 3,700m. Virtually no overnight recovery of the snowpack is expected once out of the valley bottom. An inversion may make for better AM travel in the valley bottom. Pack your sun block.
Snowpack Summary
Moist snow extends to treeline on all but the most Northerly slopes. On Southerly slopes this continues into the alpine. 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
The spring avalanche cycle will be in full swing over the next few days. Large and destructive avalanche can be expected from all elevations and running far into the valley bottom. Without an overnight freeze forecasted these events will start early, perhaps before midday.
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.