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Avalanche bulletin through Wednesday, 30 July 2014

Snowfall in high alpine regions: beware avalanche danger

Edition: 28.7., 17:00 Next update: In the event of heavy snowfall Validity

Snowfall in high alpine regions: beware avalanche danger
Edition: 28.7.2014, 17:00 / Next update: In the event of heavy snowfall
Avalanche danger
Due to intensive snowfall, the avalanche danger is increasing on Tuesday in the Bernese, Urner and Valais Alps in particular, as well as in northern Ticino. Especially in ridgeline areas, snowdrift accumulations are forming which are prone to triggering, due to moderate velocity southerly winds. The size of these drifted masses tends to increase with ascending altitude. Both new fallen and newly drifted snows can release naturally in the indicated regions and even be triggered by one sole person. Avalanches can in some places attain medium size. On Wednesday the avalanche danger will diminish somewhat from region to region. In the Bernese Alps, the danger will remain unchanged.
High altitude backcountry tours require experience in assessing the avalanche perils. In extremely steep terrain, even small sized avalanches can bring about a fall. The hazards of being swept along and falling need to be taken into consideration.
Snow and weather
Snowpack
There was by and large an area wide snow cover on glaciated north facing slopes above approximately 3000 m, elsewhere above approximately 3500 m. The snowpack was thoroughly wet for the most part. Only on north facing slopes at highest altitudes of high alpine regions was the snow still dry in some places.
Weather review to Saturday
Over the weekend there was 15 to 30 cm of snowfall in the Bernese Alps as well as in the Tödi and Bernina regions above approximately 3500 m.
On Monday morning it was partly sunny, in the afternoon skies increasingly turned heavily overcast. The zero-degree level was at about 3700 m.
Weather forecast through Wednesday
On Monday night and during the day on Tuesday, heavy precipitation is anticipated in some places. The snowfall level will drop in western regions from 3200 down towards 2600 m. In eastern regions it will be at about 3200 m. By Tuesday evening above 3500 m in the Bernese and Urner Alps and in the Upper Valais, about 50 to 80 cm of new fallen snow is expected. In the remaining regions, as well as in general at lower altitudes, much less snowfall is expected. Winds will be blowing at moderate velocity from southerly directions.
On Wednesday skies will be heavily overcast for the most part. In the Bernese Alps above approximately 3400 m, an additional 20 to 40 cm of snowfall is possible. Winds will be blowing at moderate velocity from northerly directions.
Outlook
On Wednesday night above approximately 3200 m on the northern flank of the Alps, snowfall is anticipated. On Thursday in northeastern regions it will be rainy to begin with, elsewhere partly sunny. On Friday it will be quite sunny during the morning. In the afternoon, convective cloud build-up and showers are possible.
In high alpine regions, wet snow sluffs and wet avalanches will be possible as a result of the solar radiation and rising temperatures. The avalanche danger needs to be ongoingly heeded.

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