A poor overnight freeze has bumped up the danger level at low elevations.
Weather Forecast
Unsettled convective cells will move through the area today, bringing flurries and light to moderate SW ridge-top winds. Freezing levels will rise to 1700m, then drop with the arrival of a brief, but intense cold front tonight. Rogers Pass may see 15-20cm overnight, with moderate SW winds and freezing levels hovering around 1300m.
Snowpack Summary
A weak freeze overnight, with many locations below tree-line not even reaching the freezing mark. Expect sloppy conditions low down. Last week's storm snow is well settled from warm temps and sits over crusts on solar aspects. The Feb 27 interface is down 70+cm and is more sensitive on steep solar aspects. Cornices are large and drooping up high.
Avalanche Summary
There was little in the way of avalanche activity yesterday, even with the warm temp's and intense sunshine. The exceptions were several natural size 2's that ran on south aspects at low elevations late in the day. This is something to consider today, given that the overnight temp's barely hit the freezing mark and for a very short time.
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.
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.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.