Press Release,
17.04.2012
A winter full of contrasts
Review of the winter 2011/12
The most recent winter was shaped by contrasts, from very little snowfall, icy temperatures and inaccessible valleys, to record quantities of snow, above-average temperatures, and exceptional gliding snow conditions. Fifteen people lost their lives in the Swiss Alps in avalanches.
Order of events
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Photograph: Between December and January, many stations measured record amounts of fresh snow in the 2011/12 winter. The greatest total snowfall during these months – 824 cm – was recorded in Elm in the Glarus Alps. (Photo: SLF/HU. Rhyner, 13.02.2012)
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From the daily news in January: "Andermatt inundated by snow. Snow clearing teams working around the clock. Valley cut off from outside world by avalanche danger." This winter those headlines were often in the press. However, even at high altitudes the early winter brought extremely little snow. According to the long-term snow statistics of the SLF, the last time that so little snow was lying at the start of December was in 1953. Snow eventually began to fall in earnest on December 3. By the end of the month, the lack of snow had been astonishingly reversed.
In January, snow continued to fall – in large quantities. Roads and railway lines were closed at times as memories of the extreme winter of 1999 were rekindled. Excepting the central part of the southern flank of the Alps, Upper Engadine and Val Poschiavo, above-average quantities of snow – more than 200 cm – were lying at 2000 m at the end of January. Gliding snow and full-depth avalanches in particular caused damage to property in the northern regions.
Temperatures fell appreciably at the end of January, and February remained very cold until the 20th. This spell was followed by two warm periods that introduced moisture into the snowpack. On February 29, the zero degree level rose to above 3000 m. The late winter was mild, but snow returned even to low altitudes at Easter.
Record fresh snow quantities and snow depths
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Photograph: For several months in the winter of 2011/12, the avalanche situation in large parts of the Swiss Alps was shaped by full-depth avalanches, as in Arosa, Grisons, in early March 2012. (Photo: copyright@FotoHomberger)
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Between the start of December and the end of January, two to three times as much fresh snow as indicated by the long-term average for this period was measured by more than half of the SLF stations. The total amounts of snowfall measured by many stations in the 30-day period from December 11 until January 9 threatened existing records. New records were actually set by a few stations, including 456 cm at Ulrichen (1350 m) and 192 cm at Samedan (1750 m).
Snow depths reached their maximum in January as well. In many places in Switzerland, the amount of snow lying on January 25, 2012 exceeded the depths recorded at any time since measuring commenced 60 years ago. The 270 cm registered on the Weissfluhjoch in Davos, for example, surpassed the previous record of 250 cm, posted on January 25, 1951, by 20 cm.
Very little snow fell in November, February and March. For this reason, the total fresh snow during the entire winter was just average. March was 3 to 4 °C warmer than usual, so that in many locations the large quantities of snow were reduced to normal by melting.
Snowpack and avalanches
The bare ground that received the first copious amounts of snow in December was still relatively warm. As a consequence, snow gliding was severe throughout the entire winter in the northern regions. Glide cracks formed that were several metres deep, and medium-sized full-depth avalanches were released on many occasions. In some cases, they endangered exposed roads and ski runs.
According to the assessment of the avalanche danger in the avalanche bulletin, the 2011/12 winter was a little more dangerous than the average winter overall. According to the assessment of the avalanche danger in the avalanche bulletin, the 2011/12 winter was as dangerous as the average winter. The avalanche danger was "high" (level 4) on 13 days in some regions on the northern flank of the Alps and parts of Valais and Grisons. The abundant snowfall and very strong winds gave rise to periods of high avalanche activity. In view of the large quantities of snow, on the other hand, the bonding of the snowpack was in the main favourable. The deeper layers of the snowpack were generally well bonded. In February, weak layers formed near the surface of the snowpack, where avalanches were released by people in particular. The warm temperatures at the end of February made the snowpack moist. This triggered high wet snow avalanche activity. In March, those engaging in winter sports often encountered a favourable avalanche situation. Snowfalls prompted a slight increase in the avalanche danger in April.
Fifteen avalanche victims
Compared with other winters, property damage was greater, but fewer avalanche accidents involving people occurred. 83 avalanches involving 109 people were reported to the SLF. 24 people were injured in avalanches, and 15 people lost their lives in 14 avalanche accidents. In the period until mid-April, the number of deaths remained well below the long-term average for a whole year, which stands at 25.
Avalanche bulletins
The SLF published the first daily national avalanche bulletin on December 6, 2011. From December 14, 2011 until April 15, 2012, it also published the regional avalanche bulletins. The national avalanche bulletin will continue to appear daily until further notice. It is available at www.slf.ch or with the White Risk mobile app. The bulletin is also accessible by phone in German, French and Italian, tel. no. 187 (0.90 CHF/call and min.), on Teletext page 782, and by subscription as an RSS feed. In addition, if you wish to be notified of the next bulletin during the summer via SMS, please send an SMS with the message START SLF SOMMER to tel. no. 9234. You can cancel the service at any time by texting STOP SLF SOMMER to the same number (CHF 0.20 per SMS).
An Alpine weather report in is available from MeteoSchweiz (www.meteoswiss.ch by fax on fax in German no. 0900 162 338, in French no. 0900 162 368, 2.00 CHF/min., or by phone in German on tel. no. 0900 162 138, in French no. 0900 162 168, 1.20 CHF/min.)
Further Information
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Contacts
Christine Pielmeier und Gian Darms, Lawinenwarndienst, WSL-Institut für Schnee- und Lawinenforschung SLF, Tel. 081 417 01 25, pielmeier@slf.ch, Tel. 081 417 01 24, gian.darms@slf.ch
Cornelia Accola und Julia Wessels, Kommunikation, WSL-Institut für Schnee- und Lawinenforschung SLF, Tel. 081 417 02 34, cornelia.accola@slf.ch, Tel. 081 417 02 86, wessels@slf.ch.
