Persistent weak layers
- All elevations
Swift daytime increase in danger of wet-snow and glide-snow avalanches
Swift daytime increase in danger of wet-snow and glide-snow avalanches
Main danger: weak layers inside the old snowpack. Danger zones occur mostly in wind-loaded high-altitude shady steep terrain, behind abrupt discontinuities in the terrain and in gullies and bowls. Naturally triggered avalanches are possible on very steep slopes. As a result of daytime warming and solar radiation, most slides and small loose-snow avalanches are possible on very steep sunny slopes. On steep grass-covered slopes glide-snow avalanches are possible. Backcountry activities should be terminated early in the day.
The snowpack is thoroughly wet up well into intermediate altitude terrain, and wet down to the ground. Variably cloudy skies on Monday night will generated a melt-freeze crust, sometimes capable of bearing loads, which softens up during the daytime on Tuesday, making the snowpack lose its firmness, and wet-snow / glide-snow avalanches possible in steep terrain. At high altitudes, older snowdrift accumulations have soft layers embedded, which are unlikely to trigger. Below 1500m on shady slopes there is not much snow on the ground.
Nocturnal hours: in the early part of the night, widespread dense clouds from the west. In early morning these will disperse, temperatures will drop, but not significantly. Wednesday: high altitude clouds will reduce visibility and cause diffuse radiation, but conditions will remain generally pleasant in the mountains. At 2000 m: +6 degrees. Brisk to strong W/SW winds.
On Thursday, mild and windy, with high altitude clouds. Friday: a cold front is forecast. Until then, daytime rise in danger of wet-snow and glide-snow avalanches requires caution.
Bulletin data: Avalanche Warning Service Vorarlberg (CC BY 4.0)