Avalanche winter 1999

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The months of January and February 1999 have become known as the 1999 avalanche winter . At that time there were countless avalanches in large parts of the Alpine region, from the French high Alps via Switzerland to Tyrol , with sometimes catastrophic consequences. The reason for this was three consecutive several days northwest congestion (January 26-29, February 5-10 and February 17-24), which led to long-lasting, intense snowfalls. Within just under five weeks, more than 5 meters of snow fell in large parts of the Alpine region, and for the first time the highest danger level 5 ("very high") on the European danger scale for avalanches prevailed for several days . Many traffic routes in the Alpine region were interrupted and entire valleys were cut off from the environment. Hundreds of thousands of tourists were affected. The three most devastating avalanches were in Chamonix / Montroc (France) with 12, Evolène (Switzerland) with 12 and Galtür (Austria) with 31 deaths. In Switzerland there were around 1200 avalanches with a total of 17 fatalities in buildings and on streets. The associated direct and indirect property damage amounted to more than CHF 600 million.

Weather development

At the beginning of the first congestion in Switzerland, at 1,500 meters above sea level, there was usually around 50 cm of snow, sometimes up to a meter, but in some places less. The existing snow depths were generally somewhat less than the mean up to then.

1st traffic jam (January 27–31)

On January 26th, a weak cold front reached the Alps, and as a result the temperatures dropped by around 10 ° C. For three days, a north-westerly orientation was established, the basis of which was a north-westerly high-altitude current from a strongly developed Azores high. This high-altitude current brought many humid air masses to the Alps. As a result, one meter of fresh snow fell within 3 days on the northern slopes of the Alps, with up to 150 cm of fresh snow falling in the eastern Bernese Oberland and in the Glarus and St. Gallen Alps. Only the southern Vispertal valleys, the Simplon region, Ticino, Engadin and the southern valleys of Graubünden fell less than 50 cm of fresh snow. The snowfalls were accompanied by stormy winds, so that snow was shifted widely. On January 28th the Azores high expanded and a typical bise formed and the temperature dropped. At the end of this period there was between 100 and 150 cm of snow at 1,500 meters on the north side of the Alps.

2nd congestion (February 5th - 12th)

The second congestion developed from February 4, when a mighty low stretched over Scandinavia and again led to a north-west congestion. From February 5th, the influx of cold sea air led to intense precipitation, in the higher areas than snow. Within four days in February, the low pushed several faults to the Alps. During these four days, between 40 and 120 cm of fresh snow fell at 1,500 meters along the north side of the Alps. Between 40 and 90 cm of fresh snow fell in Valais, northern and central Grisons. Up to 50 cm of fresh snow fell in the other areas. Again there was extensive snow shifting to the south exposed slopes. On February 9, a low ridge reached the Alps and the wind turned south-west, whereupon the mild, humid air was led into the Alps. The meeting of these air masses on the still cold congestion location meant that there was again intense snowfall, especially in Valais. The snow line rose to 1000 meters. Within 24 hours, between 20 and 50 cm of fresh snow fell on the northern slope of the Alps and in Lower Valais, and 10 to 30 cm in the other areas, only the southern side of the Alps remained free of precipitation. The low pressure area crossed the western Alps on February 10th and after it the wind turned north-west to north and supplied cold but dry air. During the second period, over one meter of fresh snow fell on the northern slopes of the Alps, in Lower Valais, northern Wallis, in northern Surselva and in Prättigau, and significantly more at higher altitudes. The record measurement in this period was made with the measuring system above Elm, where 257 cm of fresh snow fell within eight days.

After the second period, the effective snow depth at 1500 meters on the north side of the Alps was between 150 and 200 cm, sometimes up to three meters.

Between February 12 and 15, a weak bise set in again and brought in cold dry continental air.

3rd congestion (February 17-25)

A low over northern Europe was responsible for the third period. It led to the formation of a north-west congestion that lasted until February 25th. The snowfall began in the afternoon of February 16, initially rather moderate. It was not until February 17 that gusts and heavy snowfalls occurred, and there was an - albeit brief - drop in temperature of a good 10 ° C. On February 18, a warm front drifted on the current towards the Alps, causing temperatures to rise again; the snowfall remained strong. By February 20, the snow line rose to around 2000 meters. On the evening of February 21st, temperatures began to drop again. The snow line was on 21/22. February at around 1800 meters. In the afternoon, a cold front with embedded thunderstorms crossed the Alps under massive snowfall, with temperatures falling again by around 10 ° C. The snowfalls, which were sometimes massive, continued on February 23 and 24. This period ended when on February 25 a weak high moved from France over the Alps towards the Balkans. The temperatures rose again significantly. In the days that followed, the increase in fresh snow in the Bernese Oberland, Central Switzerland, the Glarus Alps, Prättigau and Samnaun was over 2 meters. The greatest value in this period was measured above Elm at 447 cm. In the Upper Engadin and on the southern side of the Alps, the increase in fresh snow was significantly lower. At the end of the third period there is almost always over 200 cm of snow at 1500 meters. In the eastern Bernese Oberland even over 300 cm.

Follow-up time

March 1999 was generally mild and too dry on the north side of the Alps. On the southern side of the Alps, on the other hand, two southern reservoirs brought larger amounts of fresh snow. On April 11, a cold front reached the Swiss Alps, which brought large amounts of fresh snow in the Lower Valais and on the northern slopes of the Alps, with massive snow loads being caused by the strong winds. On April 14, the winds turned south-west to south on the face of a partial low coming from the British Isles. As a result, there was a foehn storm in the valleys on the north side of the Alps. On the southern side of the Alps, however, there was massive snowfall. This partial low remained hanging over the central Alpine ridge for around two days, especially on April 16, when up to 100 cm were measured within 24 hours. Whereby it came to massive snow loads again. On April 17th, the partial low moved further towards the Mediterranean and the snowfalls stopped. In the Gotthard area there was between 150 and 200 cm of fresh snow in this short period. In the central and southern Alps between 100 and 150 cm of fresh snow, in the west and east between 50 and 100 cm of fresh snow.

Avalanches

This article or paragraph describes the situation in Switzerland . Help us to describe the situation in other countries.

The following number of avalanches fell in Switzerland.

Period Northern Alpine slope North Grisons Valais Southern side of the Alps + Upper Engadine
27.-31. January 041 011 114 k. A.
February 5-12 176 062 181 03
17th to 25th February 377 188 245 16
16. – 20. April 063 026th 015th 43

Avalanches with dead in Switzerland

In the winter of 1998/1999, avalanches claimed a total of 36 lives in Switzerland. Of these, 17 were victims of the heavy snowfalls described here , the remaining 19 victims were involved in so-called tourist accidents. Only those avalanches whose victims are related to the heavy snowfalls are shown in the list.

local community Place / local name Date / time Buried dead Damage Remarks
Lauterbrunnen Wengen , Oberland restaurant February 5th, probably at 2:00 am 02 02 Oberland restaurant completely destroyed, Männlichenbahn valley station buried and cabins damaged, Wengen-Kleine Scheidegg railway line buried
Lavin Main street Lavin-Giarsun 6 February 15:23 04th 01 2 cars destroyed Main road not blocked
Evolène see: Evolène avalanche accident February 21, 8.30 p.m. 13 12 8 houses, 5 barns, 4 chalets and several alpine huts destroyed, 2 houses, 8 chalets damaged, at least 9 cars total loss, major damage to the forest and infrastructure (telephone and power lines) 1 event with multiple avalanches
Silenen UR Bristen, Egg settlement 23 February 7.30 01 01 1 house destroyed, several buildings and Golzern cable car damaged
Münster-Geschinen Geschinen February 24th 5pm 01 01 1 house destroyed, 2 houses and 1 garage badly damaged Avalanche barrier became ineffective

See also

Individual evidence

  1. ↑ Avalanche winter 1999, Chapter 2.2.1, pages 32–33
  2. ↑ Avalanche winter 1999 Chapter 2.2.1, pages 33–35
  3. ↑ Avalanche Winter 1999 Chapter 2.2.1, Pages 35–39
  4. ↑ Avalanche winter 1999 Chapter 2.2.1, pages 39–40
  5. ↑ Avalanche Winter 1999 Chapter 2.8 Pages 91 + 92 Figures 2.32 + 2.33
  6. ↑ The avalanche winter 1999 Chapter 3.3 "Accidents with fatal consequences for people" pages 172–194

literature

  • The avalanche winter 1999. Event analysis . Federal Institute for Snow and Avalanche Research, Davos 2000, ISBN 3-905620-80-4 .
  • Living with the avalanche risk. Lessons from the avalanche winter 1999 . Federal Office for the Environment, Forests and Landscape (BUWAL), 1999.
  • CJ Nöthiger: The avalanche winter 1999. Case study Elm (Canton Glarus). Indirect effects on the local economy . Federal Institute for Snow and Avalanche Research, Davos 2000.

Web links

Individual reports: