Central Prealps
Gersau
Stable day. Low, with wet snow and gliding snow named together — one of them visible at the surface, the other buried.
Day Risk Profile
Avalanche Problems
Wet snow + Gliding snow
1
Field notes
Wet snow
Rolling snowballs, deep penetration when you step or ski, and small natural slides are clear signals that the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is losing strength. After a clear, cold night the surface often freezes into a strong supporting Layer of hard-compacted snow resulting from a melt-freeze process or wind.EAWS glossary, and conditions are favourable in the early morning. After a warm, overcast night, the problem may be present from the start of the day. Plan early returns and watch the runout zones below you.
Gliding snow
Almost impossible to predict precisely, even when the warning signs are visible. A crack visible on the snowpack surface formed by snow-gliding on steep, and particularly grass-covered slopes. Areas below slopes with visible glide cracks should be avoided whenever possible due to threat of gliding sluffs or avalanches.EAWS glossary — gaps that open in the Snow deposited on the ground in a multiplicity of layers.EAWS glossary down to the ground — are often precursors to release, but they don't tell you when. A glide avalanche can release minutes after the cracks appear, or weeks later, or not at all. Some release without any visible warning. Avoid lingering anywhere near glide cracks: above them, alongside them, or below in the runout.
Snowpack & Weather
Snowpack
With the mild temperatures of the last two weeks, moisture penetration into the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is already well advanced. At present, it is only increasing slowly. North-facing slopes at altitudes between 2200 and 2500 m are most susceptible to moisture penetration. On east- and west-facing slopes, the critical altitudes are somewhat higher, at approximately between 2500 and 2800 m. On south-facing slopes, moisture penetration into the snowpack extends as far as the Areas above approximately 3000 m (particularly glaciated areas).EAWS glossary. It is on these Direction in which a slope faces as indicated by compass direction of the fall line; i.e. a north slope faces in a northerly direction.EAWS glossary and at these altitudes that isolated large wet The abrupt release of a slab of snow on a mountain slope. After crack initiation and crack propagation in a weak layer the released slab comprises 3 elements: The weak layer, the gliding horizon and the slab. If the slope angle is steep enough, the slab will glide down. If the slope is not steep enough, the slab will settle down on the failed weak layer. Possibly a whumpf sound will follow due to air pressed out of the weak layer. The fracture line will be sharp edged.EAWS glossary may be triggered naturally.
In Grisons, the Snowpack layer in which the crystals are poorly bonded and the layer has the potential to fail. Typical crystals in dry weak layers causing avalanches are : precipitation particles; surface hoar; faceted crystals; hollow crystals; graupel. Generally >1mm in size, loose grains with few bonds Wet weak layers can be formed by all snow crystal/grain types.EAWS glossary in the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are the least deeply buried, and it is here that wet The abrupt release of a slab of snow on a mountain slope. After crack initiation and crack propagation in a weak layer the released slab comprises 3 elements: The weak layer, the gliding horizon and the slab. If the slope angle is steep enough, the slab will glide down. If the slope is not steep enough, the slab will settle down on the failed weak layer. Possibly a whumpf sound will follow due to air pressed out of the weak layer. The fracture line will be sharp edged.EAWS glossary are likely also to be triggered by human activity.
At higher altitudes, the Snow deposited on the ground in a multiplicity of layers.EAWS glossary is still dry. There are still Snowpack layer in which the crystals are poorly bonded and the layer has the potential to fail. Typical crystals in dry weak layers causing avalanches are : precipitation particles; surface hoar; faceted crystals; hollow crystals; graupel. Generally >1mm in size, loose grains with few bonds Wet weak layers can be formed by all snow crystal/grain types.EAWS glossary in the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary, but no more dry avalanches have been reported in recent days.
Weather review for Tuesday
It was mostly sunny, and cloudy at times on the central and eastern parts of the northern flank of the Alps.
Fresh snow
-
Temperature
At midday at 2000 m, between +4 °C in the southwest and 0 °C in the northeast
Wind
Light to moderate from westerly directions
Weather forecast to Wednesday
In the far south, the night into Wednesday will be cloudy with some rain; it will become increasingly sunny during the day. In the north, it will be mostly sunny after a mostly clear night.
Fresh snow
-
Temperature
At midday at 2000 m, between +4 °C in the southwest and +1 °C in the northeast
Wind
Light.
Outlook to Friday
After clear nights, it will be sunny during the day with light winds. The zero-degree level will be just below 3000 m on Thursday and will rise to around 3300 m on Friday.
The danger of dry avalanches will not change significantly. The danger of wet avalanches will increase during each day. Off-piste skiing and hut ascents should be completed in good time.