Lower Valais
Montana
Day Risk Profile
Avalanche Problems
Persistent weak layers
1
Field notes
Persistent 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 are very challenging to recognise. Distinctive noise (resembling a “whumpf” sound) occurring when a weak layer beneath a slab collapses. The air of the weak layer is forced outside the snowpack, with the resulting whumpf sound being heard. The sound usually indicates an unstable situation and can be accompanied by surface cracking. A whumpf is a clear avalanche alert.EAWS glossary sounds and shooting cracks are typical when present, but you can have a serious weak layer with no warning signs at the surface. Knowledge of how the Snow deposited on the ground in a multiplicity of layers.EAWS glossary has evolved is essential. SLF's travel advice is direct: travel conservatively, avoid terrain where the consequences of being caught are large, and treat the history of weather and snow as more important than what you can see today. Read the full bulletin.
Gliding snow
2
Field notes
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
In the regions south of a line Rhône - Rhine, the persistent 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 that have been a feature since the beginning of January are still present. The number of places where avalanches can be triggered by human activity in the weak layers of the Snow layers deposited from earlier precipitation, prior to fresh fallen snow. Old snow layers consist of metamorphosed snow crystals.EAWS glossary are continuing to decrease. However, avalanches may still become large.
In the regions north of a line Rhône - Rhine and in the extreme west of Lower Valais, 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 deposited on the ground in a multiplicity of layers.EAWS glossary are mostly thickly covered. Triggering by human activity is unlikely.
As a consequence of the falling temperatures, the continued moistening of the Snow deposited on the ground in a multiplicity of layers.EAWS glossary and of the deeper 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 is slowing down. The probability of triggering Avalanche of wet snow masses. Flowing more slowly than dry avalanches; usually for shorter runout distances, however with greater impact on obstacles due to higher snow density.EAWS glossary increases only a little during the day. Gliding avalanche activity is continuing to decrease. Gliding avalanches can however become large, especially in the snowier west.
Weather review for Monday
Sunday night into Monday was mostly clear in the west and only partly clear in the east and south. During the day there was only a little sunshine on the southern flank of the Alps and on the eastern part of the northern flank of the Alps, while elsewhere it was mostly sunny.
Fresh snow
-
Temperature
At midday at 2000 m, around +2 °C
Wind
Light, occasionally moderate southerly
Weather forecast to Tuesday
Monday night into Tuesday will be mostly clear in the north. In the early morning, it will still be mostly sunny in this region. During the day, cloud cover will gradually increase from the west. As a result, rain showers are possible over the Jura. Along the Main Alpine Ridge and south of it the overnight, conditions will be mostly cloudy. During the day it will be mostly cloudy, especially on the central part of the southern flank of the Alps, with showers overnight to Tuesday and on Tuesday afternoon. It will be sunnier in southern Grisons.
Fresh snow
- A few centimetres on the central part of the Main Alpine Ridge above 1500 m
Temperature
At midday at 2000 m, between +1 °C in the north and -2 °C in the south
Wind
- From southerly directions
- Mostly light, sometimes moderate as the day progresses in the regions exposed to the foehn wind
Outlook to Thursday
Tuesday night into Wednesday will be partly cloudy. During the day it will be partly cloudy in the north with bright spells, especially in the inneralpine regions of Valais and Grisons. Showers are possible in the Jura and the Prealps. In the south, it will be mostly very cloudy with bright spells. Overnight to Thursday, it will be mostly overcast with widespread light snowfall above approximately 1400 m. During the day it will clear rapidly in the west and south, but it will only be partly sunny on the central and eastern parts of the northern flank of the Alps and in northern Grisons. There will be an often moderate wind at high altitudes, shifting from a southerly to a northerly.
The danger of dry avalanches will increase somewhat, especially on the northern Alpine ridge. In addition, the danger of wet and gliding avalanches will increase a little during the course of the day. Touring and off-piste descents should be completed in good time.