Watch for wind slabs immediately lee of ridge crest, pay attention to cornices and remember that we're still dealing with a persistent slab problem. Choose well-supported lines and travel early to take advantage of the overnight re-freeze.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain on Wednesday
Weather Forecast
Temperatures are expected to be slightly cooler Wednesday as we move into a pattern across the province that remains quite "winter-like." WEDNESDAY: Scattered cloud cover with potential for some clearing in the afternoon, freezing level beginning around 600 m rising to about 1700 m, light southwest wind, trace of precipitation possible.THURSDAY: Broken cloud cover, freezing level beginning around 600 m rising to about 1500 m, light southerly wind, 2 to 5 mm of precipitation possible.FRIDAY: Clear skies in the morning building to broken cloud cover in the afternoon, freezing level beginning near valley bottom rising to about 1600 m, moderate southwest wind, no significant precipitation expected.
Avalanche Summary
Loose wet avalanches to size 2 were reported from all aspects between 1000 and 2300 m Monday. In the neighboring Glacier National Park, loose wet avalanches to size 3 were reported from solar (south and west) aspects to size 3 between 2000 and 2300 m. A size 1.5 storm slab was ski cut from a northwest facing feature at 2400 m illustrating that isolated storm/wind slabs are still in play at upper elevations.On Sunday natural loose wet avalanches to size 2 were reported from all aspects (including north) as high as 2800 m.
Snowpack Summary
5 to 10 cm of new snow fell Saturday with moderate southerly wind. This snow rests on a crust that is present on all aspects below 2000 m, and extends up to about 2500 m on south facing aspects. The storm snow be be sitting on surface hoar on polar aspects (north and east) at upper elevations. The main concern is the mid-March Persistent Weak Layer (PWL) which is now 60 to 110 cm below the surface. This layer is composed of a crust on all aspects at low elevations. At upper elevations the layer presents as a crust on solar aspects (those that face south and west) and buried surface hoar on polar aspects. The reactivity of this interface has been steadily decreasing and while the likelihood of triggering a deeper persistent slab avalanche is lowering, the consequence of doing so remains high. Persistent slab avalanche activity on polar (north and east) aspects has dramatically decreased and solar (south and west) aspects are expected to be the most suspect over the next few days.Deeper persistent weak layers from January and December are still being reported by professional observers, but are generally considered dormant.
Problems
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.