Spring is officially here! Our daily forecast will stop as of today, but we will update if needed. Remember that snow stability is directly related to temperatures. Early starts and solid freezes are essential for safe travel.
Weather Forecast
The predictable spring pattern appears to be with us now. The next few days will see daytime freezing levels approach treeline and evening lows just below zero. The winds will be light for the next 3 days. Flurries will also be ongoing, however amounts will be low.
Avalanche Summary
Nothing noted, but our field day was done by 9 am. Likely some loose wet to sz1.5 in the afternoon with the warmth and light rain.
Snowpack Summary
Wet. Last night saw rain up to 2300m with extended warm temps. Eventually the rain turned to snow, but not until late in the night (or early in the morning-depends on how you look at it). This made for a very marginal freeze with 5-10cm of moist snow on the surface. Right now valley bottom snow is isothermal, treeline snow is seeing a daily freeze/thaw cycle and the alpine is seeing surface crusts on all aspects that are gradually penetrating to the deeper layers. A late, but classic spring change to the entire snowpack is underway. With the extended warmth cornices are an increasing problem. Treat them with caution, whether they are above or next to you.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.