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Full avalanche bulletin PDF

Avalanche bulletin until Thursday, 23 May 2013

Beware snowdrift at high altitudes

Edition: 21.5., 17:00 Next update: 23.5., 18:30 Validity

Beware snowdrift at high altitudes
Edition: 21.5.2013, 17:00 / Next update: 23.5.2013, 18:30
Avalanche danger
New fallen and newly drifted snow masses are the major peril.
On Wednesday the avalanche prone locations are to be found on north facing slopes in high alpine regions more than anywhere else. Older snowdrift accumulations can in some places be triggered as avalanches by one single backcountry skier or freerider and should be evaluated with great caution.
On Thursday the avalanche danger is expected to increase somewhat as a result of strong northwesterly winds. In those regions where there is fresh fallen snow and in high alpine regions in general, drifted masses of snow are expected to accumulate which can be triggered as avalanches even by one single skier or freerider. The danger zones are to be found in those regions along the northern flank of the Alps where snowfall was heaviest above approximately 2500 m, elsehwere in high alpine regions more than anywhere else. Backcountry tours require experience in assessing avalanche hazards.
Particularly on the southern flank of the Alps, generally small sized, wet avalanches are possible during the course of the day as a result of solar radiation.
Snow and weather
Review through Whit Monday, 20.05.2013
On the Monday and Tuesday after Pentecost skies were frequently overcast. There was intermittent snowfall, particularly in southern regions. The snowfall level was at approximately 1700 m. Between Sunday evening and Tuesday evening above approximately 2200 m in the central sector of the southern flank of the Alps, there was 30 to 50 cm of new fallen snow. Along the remaining Main Alpine Ridge from the Simplon region to the Bernina Pass there was 10 to 30 cm of fresh fallen snow, elsewhere about 10 cm of snowfall widespread.
Southwesterly winds were blowing at light to moderate velocity. At high altitudes and in high alpine regions, fresh snowdrift accumulations formed.
Forecast through Thursday, 23.05.2013
On Wednesday and Thursday in northern regions, repeated snowfall is anticipated. The snowfall level will drop from 1700 m down to about 1000 m by Thursday evening. In the inneralpine regions, isolated bright intervals are expected, more extensive bright spells are anticipated in southern regions.
Between Tuesday evening and Thursday evening above approximately 2000 m, the following amounts of snowfall are expected:
  • northern flank of the Alps from the eastern Bernese Oberland to Liechtenstein: 30 to 50 cm
  • remaining northern flank of the Alps, Lower Valais, northern Grisons: 10 to 30 cm
  • remaining regions, less; on the southern flank of the Alps, no snowfall
On Wednesday a moderate northwesterly wind will be blowing, on Thursday at moderate to strong velocity. In those regions with fresh fallen snow and in high alpine regions in general, fresh snowdrift accumulations are expected to form.
Outlook
On Friday and Saturday, conditions will remain variable. Above approximately 1000 m intermittent snowfall is expected. The avalanche danger will remain heightened, particularly in those regions with new fallen snow and in high alpine regions in general.
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Weather information in collaboration with MeteoSwiss. Alpine weather report: www.meteoswiss.ch

  
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