Condtions have improved greatly in a week. Good group management and appropriate terrain selection is still critical, as always.
Weather Forecast
Light, convective snow is forecast for the park today, also with strong solar inputs likely. Alpine temps will rise to -5. Strong temperature fluctuations are expected between day and nighttime temperatures over the next three days. Over this period the skies will continue to clear as a high pressure system moves over the region.
Snowpack Summary
30cm of storm snow is dry down to 1400m, with sun crust on solar aspects. Strong southerly winds deposited this snow on lee aspects at treeline and the alpine. The storm snow is reactive to rider triggering in steep and unsupported terrain, especially at treeline. The March 11 surface hoar-suncrust weak layer is down about a meter.
Avalanche Summary
No new natural avalanches were observed along the highway corridor yesterday in the park. A small avalanche cycle occurred on Wednesday night, mostly from steep start zones on Mt. MacDonald. Also on Wednesday, explosive testing produced a size 1 avalanche on a north aspect at treeline.
Confidence
Due to the number of field observations
Problems
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.
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.
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.