Loose avalanches triggered by solar warming is the main concern today. If the sun remains strong in the afternoon, watch for a moist surface indicating the snowpack is heating up. Limit exposure to hot spots above you like rocks and trees.
Weather Forecast
Clear to scattered skies are forecast for the park today. Temperatures will rise, expect alpine temps around -4 and a 1200 m freezing level. Winds over the next three day period are forecast to be light with no precipitation, strong diurnal temperature fluctuations and lots of solar input during the day.
Snowpack Summary
25cm 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 may be 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
A couple loose avalanches up to size 2 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
Timing or intensity of solar radiation is uncertain
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.
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.