Avoid avalanche terrain!
Strong sunshine and above freezing alpine temperatures are causing a widespread natural avalanche cycle
Widespread large natural avalanches are expected
Cornices are being weakened by strong sun and hot alpine temperatures. A falling cornice itself is a major hazard but may also trigger large destructive slab avalanches on the slopes below.
This crust-facet combo (Feb 3rd) was created by a rain event followed by an extended cold, clear period without snow earlier this month. 80-140cm now sits on this persistent weak layer. Natural avalanche activity is expected on this layer as warm temperatures continue to penetrate the snowpack.
With above freezing temps into the alpine, loose snow avalanches are expected to run on all aspects as the snowpack warms.
Since the warm up began on Friday we have seen numerous loose and wet slab avalanches from solar aspects, some very large and failing on the Feb 3rd layer. Notably a size 4 from the west face of Cheops and size 3 beside the Grizzly couloir
Expect natural avalanches to increase in size and frequency with continued warming.
Natural avalanches on the persistent weak layer (over 1m deep) are expected to become widespread as the warmth penetrates deeper into the snowpack.
Expect a very thin crust to form overnight that will break down quickly by mid morning from above zero temps and intense sun. When that happens the upper snowpack will turn to mush.
A previous suncrust, down 20-40cm, may make a sliding layer for wet slabs.
80-140cm of settled snow sits above a sugary facet layer. These facets are poorly bonded to the widespread, firm crust from Feb 3rd. This is a significant persistent weak layer and will be a concern for the foreseeable future.
The warm weather will continue for two more days keeping the avalanche danger high. By mid week the freezing level (FZL) will begin to lower and temps return to more seasonal values and snow on Wednesday.
Tonight: Alpine low 2°C, light W winds, FZL 1100m with a temperature inversion.
Mon: Warm and sunny, low 1°C, high 3°, FZL 2700m, light W winds.
Tues: Mix of sun and cloud, low 1°C, high 4°C, FZL 2100m, light W winds.
