Extent of solar radiation and warming influence is uncertain. Use extra caution as the day progresses especially on South facing slopes.
Weather Forecast
Sunday night and Monday: The ridge of high pressure continues to bring dry conditions, well above normal temperatures. Inversion with temperatures reaching + 1 C in the alpine, few clouds cover with valley clouds and light NW winds. Freezing level rising during the day to 1200 m.Tuesday: The ridge is moving slowly Eastward bringing more mild temperatures, few clouds and valley clouds and lighter winds from the NW. Slightly cooler temperatures, with freezing level lowering around 800 m. Wednesday: A weak system should reach the region later during the day bringing light precipitation (16 mm), cooler temperatures (-7 C) and moderate Southerly winds.
Avalanche Summary
A slab avalanche size 2 and numerous loose avalanches would have been triggered yesterday on steep sun exposed slopes.
Snowpack Summary
The warm temperatures and solar radiation forecasted for tomorrow could weaken the windslabs and persistant slabs, especially those found on steep South facing slopes. If surface snow becomes moist, loose wet avalanches could also take place, and even though small in size, they could become a problem if thrown off your feet in a terrain trap. As a general picture, around 40-60 cm settled storm snow sits above surface hoar, a sun crust (on steep S to SW -facing slopes) and facets. Results on the surface hoar layer vary from sudden planar to resistant planar in the moderate to hard range. It appears to be more reactive in the Northern part of the region, especially in the 1900 to 1500 m. range. The distribution of these weaknesses is patchy, but where they exist, they may be triggered by the warming trend or under with the weight of a person or snowmobile. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is generally considered inactive.
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.