Pay close attention to terrain selection and signs of instabilities such as shooting cracks and whumffing.
Weather Forecast
Low pressure in the gulf of Alaska is driving a warm westerly flow over the park. Overnight temps will drop below freezing but will rise to 2,100m tomorrow. Flurries at upper elevations may shed 5cm with moderate SW winds. Temperatures will cool off on Friday and into the weekend.
Snowpack Summary
Moderate SW winds are building a wind slab at treeline and into the alpine. These slabs may be up to 40cm thick and are weekly bonded to the snowpack below. The mid-pack consists of buried wind and persistent slab with a failure plane down 60cms. In the valley bottom the snowpack is very week and unconsolidated making for tough trail breaking.
Avalanche Summary
Field team in the Whistler Creek drainage reported isolated large avalanches to size 3 in the alpine. It is possible to trigger slab avalanches from a distance at treeline and above in wind loaded features; as was done on the 16th to size two in the Whister Creek drainage.
Confidence
Timing or intensity of solar radiation is uncertain
Problems
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.
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.