Variable spring conditions are present in the park. Glide cracks and cornices continue to be a unpredictable hazard. Avalanche hazard will increase during the overnight period with an incoming storm.
Weather Forecast
Light snow will begin mid-day today turning to moderate this evening through the overnight period. Light precipitation will continue over the weekend. During the storm winds will be moderate-strong southwesterly. Freezing levels will continue to fall over this three day period. Expect alpine temperature around -5 today.
Snowpack Summary
Up to 60 cm of storm snow that fell two days ago, with moderate South winds have created a storm slab in the alpine and treeline. These slabs overly a crusts on most aspects. Surface hoar has been observed at this interface above 2400 m on north aspects. Below treeline, the snowpack has become isothermal, frozen in the mornings, mush by afternoon.
Avalanche Summary
Yesterday we observed a small avalanche cycle in the new snow. Moist loose avalanches were not reaching the end of their runnouts, but were observed up to size 2.5 along the highway corridor. On Grizzly shoulder, skier triggered size 1 avalanches occurred on steep, S/SW terrain on a crust. Glide cracks and cornices are still unpredictable hazards
Confidence
Timing of incoming weather systems is uncertain
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.
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.