Review of the winter 2012/2013

Press Release, April 17, 2013

In the Swiss Plateau in particular, the winter of 2012/13 was long, cold and accompanied by large quantities of snow. It has been 26 years since it snowed on so many days at low altitudes. A lot of snow was lying in the mountains, especially in the west and north.

Order of events

Figure 1: A slab avalanche triggered remotely by skiers at approximately 2200 m on the Hüreli above Davos (canton Grisons). It was released deep in the snowpack (photo: Patrizia Weber, 10.02.2013).

Countless cold and overcast days, and snowfall that continued until after Easter – in the Swiss Plateau the winter seemed to be never-ending this year. This impression was corroborated by hard facts: according to measurements taken by MeteoSwiss, winter 2012/13 was exceptional in the regions from Bern to St Gallen, as regards snowfall and temperatures in particular. The winter was heralded on two occasions as early as October, when snow fell down to low altitudes. Even Bern and Zurich appeared in a white mantle. The months from December until March were a little colder than usual. In combination with the elevated precipitation frequency, this resulted in quantities of new snow at the MeteoSwiss stations in the Swiss Plateau around twice as large as normal. Between December and March it snowed here every four to six days on average. 1986/87 was the last winter in which so many days of snowfall were recorded. In the mountains, snow depths were above average in the west and north. At the Hasliberg (1825 m) and Schwägalp (1350 m) stations, for example, 190 cm and 142 cm of snow respectively was still lying at the end of March. In northern and central Grisons, in contrast, only average snow depths were measured. Depths were below average in both Engadine and on the southern flank of the Alps.

Avalanches claimed the lives of 21 victims

Figure 2: This large wet snow avalanche was released naturally during the night of 22 December in Meiental near Leweren (Wassen, canton Uri) – avalanche activity on the following day was the highest of winter 2012/13. The avalanche started in a southwest facing ravine and reached the main road. Here it was deflected by an existing wall of snow before following the course of the road, around several bends, for around 150 m out of the valley towards Husen. Remarkably, the avalanche did not cause any property damage (photo: Hans-Martin Henny, 23.12.2012).

In the northern and western regions where a lot of snow fell, the snowpack was well bonded over a wide area. In most cases, therefore, only fresh layers of snow and snow drift accumulations could be released as avalanches. The situation was different in the southern regions of Valais and large parts of Grisons, where near-ground layers of the snowpack were weakly bonded, so that avalanches were released even in deep layers of the snowpack. The occurrence in the avalanche bulletin of the individual danger levels corresponded more or less to the long-term average. The most frequently forecast danger level was moderate (level 2). For the 2012/13 winter, 135 avalanche accidents involving a total of 212 people had been reported to the SLF by the deadline on 15 April. Of these, 44 people were injured and 21 lost their lives. The numbers reflect the long-term average for the period until mid-April.

Avalanche bulletins

The SLF issued the first daily avalanche bulletin of the winter on 27 November 2012. This was also the date on which the revised bulletin format with the interactive danger map was launched. From 4 December 2012 until 14 April 2013, a danger assessment was published twice a day. For the time being, the avalanche bulletin will continue to appear daily at 5 pm. It is available at www.slf.ch or with the SLF app “White Risk”. Users can also subscribe to an RSS feed or the text messaging service, which, during the summer, draws attention to the publication of an avalanche bulletin in the event of significant snowfall. (To order the service, text START SLF SOMMER to 9234. To unsubscribe, text STOP SLF SOMMER to 9234. CHF 0.20/SMS.) An Alpine weather report in German is available from MeteoSwiss (www.meteoswiss.ch), by phone on 0900 162 138, (CHF 1.20/min.), or by fax on 0900 162 338 (CHF 2.00/min.).

Further Information

• Winterflash 2012/13 (more detailed review of the winter in German and French)
• Overview of avalanche accidents

Download

• Images and graphs (Download)

Contacts

Gian Darms, Avalanche warning, WSL Institute for Snow and Avalanche Research SLF, phone 081 417 01 24, gian.darms@slf.ch

Martin Heggli, Communication, WSL Institute for Snow and Avalanche Research SLF, phone. 081 417 03 56, martin.heggli@slf.ch