Extraordinary snow accumulations over parts of central Europe during the winter of 2005/06 and weather-related hazards

During the winter of 2005/06, record-breaking snow accumulations were observed in many locations in south-east Germany, large parts of Austria and in the low mountain ranges along the Czech/German as well as Czech/Austrian borders. In the lowlands, low mountain ranges and eastern Alpine valleys of the above-mentioned study area, the snow mantle reached its maximum depth in early to mid-March, with many stations reporting snow depths between 40 and 60 cm in the morning hours of 7 March 2006 (Figure 1), with a few readings of more than 100 cm, e.g. Lunz am See 139 cm (Eastern Alps, Austria, altitude of 615 m above sea-level (a.s.l.)) and Zinnwald-Georgenfeld 150 cm (Erz Mountains, Germany, 882 m a.s.l.). Shortly after this date, widespread snow depths of more than 100 cm were also observed in the Bavarian and Bohemian Forests and the Austrian Forest Quarter. The picture taken at Neureichenau (Bohemian Forest, Germany) on 12 March 2006 gives a good impression of the landscape buried under the deep snow (Figure 2). As seen in the picture, local residents had to remove the snow from the roofs of their houses to avoid collapse. The winter of 2005/06 was not only notable in terms of the snow depth at the end of the winter season, but also in terms of snow-cover duration and intermittent heavy snowfall events in the low-lying areas of the study region. Among the most momentous weather-related hazards were the collapse of several roofs under the heavy weight of the snow. For example, the breakdown of the dome of an ice skating hall at Bad Reichenhall (Germany) on 2 January killed 15 people and injured over 50. As many winters in the last two decades were unusually mild and, consequently, marked by a poor snow cover, the winter of 2005/06 was perceived by the local residents as being extremely snowy, cold and long. People will commemorate the winter of 2005/06 as being the severest in decades; at some locations the severest within living memory. In the present contribution, we will highlight that from the climatological standpoint the winter was neither unusually wet nor cold, but characterised by the absence of significant thawing episodes. We will relate this to the anomalous frequency and persistence of two particular circulation weather types. This article will also give a more detailed account of the weatherrelated hazards and will briefly discuss if this type of extreme weather is likely to be expected more frequently in the future. For these aspects, the winter period is defined as the time from the beginning of October to the end of March. The winter of 2005/06