Careful decision making is still required with lingering persistent weak layers. With snow in the forecast, expect avalanche hazard to increase.
Weather Forecast
A cold front arrivers later this morning with up to 20cm of new precipitation for the area by Saturday evening. Freezing levels rise to 1700m today, meaning a mix of rain and snow at lower elevations. Winds will be light from the SW with occasional gusts to 40km/h. Weather remains unsettled into next week with periods of sun mixed with flurries.
Snowpack Summary
Recently formed wind slabs exists on lee features above treeline with 10-20cm of soft powder in sheltered areas. Below 2000m, the upper 20cm is moist in the afternoon. Storm instabilities down 30-60cm are present but becoming less reactive. Persistent layers exists down 150cm (February crust) and near the base of the snowpack (November crust).
Avalanche Summary
2 size 2.5 avalanches were observed from the highway corridor on the north face of Mt MacDonald. These slides were triggered during a spike in wind speed late in the day on March 22nd. There have been reports of cornices failing and triggering large slabs in steep terrain in areas near Glacier National Park.
Confidence
Intensity of incoming weather systems 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.