Weather Forecast
Monday: heavy snowfall continuing overnight into Tuesday - strong to extreme southwest winds - freezing level at 1300m Tuesday: continued heavy snowfall - strong southwest winds decreasing throughout the day- freezing level at 1000m Wednesday: a mix of sun and cloud as a clearing trend develops - light and variable winds - freezing level at 900m
Avalanche Summary
Explosives control on Saturday produced numerous size 1.5-2 avalanches that ran on the March 26th interface. Some of these avalanches ran sympathetically with other slides, or remotely at distances of up to 300m. On the same day, a size 2 skier-triggered windslab avalanche occurred on a southwest aspect at treeline in the Fitzsimmons Range. On Sunday, ski cutting produced numerous size 1-1.5 windslab avalanches that ran within snow that fell over the previous 24hrs. Expect widespread wind and storm slab avalanche activity with potential to step down to the deeper March 26 interface with weather forecast for Monday.
Snowpack Summary
10-15cm of new snow has added to the 75-100cm that overlies surfaces that were buried on March 26. This interface consists of a crust which exists on all aspects except true north facing slopes at treeline and in the alpine, where small surface hoar may be present in sheltered places . This week's snow continues to be redistributed by consistently moderate to strong variable winds, forming windslabs in unsuspecting locations. Below the March 26 interface, the snowpack is well settled and bonded, with further strength gains deeper in the pack. Cornices are huge, and will continue to grow with the forecast weather pattern.
Problems
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.