One storm warning seems to be replacing the next, and the effects of the storm lows “Ylenia”, “Zeynep” and currently “Antonia” have also recently been seen in Austria. The Central Institute for Meteorology and Geodynamics (ZAMG) confirmed to the APA that the winter in some regions of Austria was extreme in this respect, in Vienna one could even experience one of the stormiest winters of the past 70 years, as an evaluation shows.
Overall, an analysis of wind data over long periods of time is more difficult than other meteorological variables such as temperature. The cause lies in the measuring systems, which have changed significantly over the decades, and the wind can also vary greatly over small areas. Air pressure data, for example, is therefore used for long-term statements on possible trends in storm activity.
In Vienna, however, it has definitely been unusually stormy in the past few weeks. “An average winter over the past 30 years brought five days with gusts of wind of at least 80 km/h at the Vienna Hohe Warte weather station. This year there have already been twelve stormy days,” said ZAMG climatologist Alexander Orlik. “The last winter in Vienna was similarly stormy in 2006/07 with 13 storm days. In the last 70 years or so it was significantly more only in the winter of 1974/75 with 17 storm days and in the winter of 1975/76 with 21 storm days.”
In Innsbruck, for example, this winter was also exceptionally stormy. So far, seven days with at least 80 km/h have been registered at the Innsbruck Airport weather station, in an average winter there are three. There were significantly more storms in Innsbruck than this year in winter 2019/20 with eleven stormy days.
On the Feuerkogel in Upper Austria (1,618 meters above sea level) this winter has brought 33 days with wind gusts of at least 100 km/h. In an average winter, 21 days with at least 100km/h can be expected on the Feuerkogel. This season has been completely different so far at the Tyrolean Patscherkofel (2,247 meters), because this winter there have only been seven days with at least 100 km/h, the average is 13. The highest value in recent years was in winter 2013 /14 with 35 stormy days.
There are large-scale storms in Central Europe and thus in Austria, especially in winter and autumn. In these seasons, the temperature differences over the North Atlantic are greatest, the ZAMG explained the necessary meteorological ingredients. Here, at the relatively sharp boundary between warm air in the south and cold air in the north, low-pressure areas often form, which move from the Atlantic to Europe.
If there is also a weather situation on the Atlantic – like this winter – with a strong low near Iceland and a strong high over the Azores, then there will be a strong westerly current and it will be very windy or stormy for a long time. In meteorology, this is referred to as a positive phase of the North Atlantic Oscillation (NAO). A negative phase of the NAO, on the other hand, brings weak and mostly dry weather in central and northern Europe – and rather damp weather in southern Europe. However, the NAO is also known for its strong differences over the years and decades.
According to ZAMG, when asked whether man-made climate change plays a role here, the storm lows over the North Atlantic, which are relevant for Europe with regard to large-scale storms, show strong fluctuations in the observation data of the past decades instead of clear trends in frequency and showed intensity. However, climate models show that winter storm lows could become more intense in the future, especially in the northern half of Europe. Due to the rising sea level, the storm surges associated with the storm lows will become more dangerous in the long term in coastal regions.
“In general, however, the resilience of all of these statements for wind is still low due to the poor data situation and the physical complexity, in contrast to all directly temperature-dependent variables such as heat and drought,” said Marc Olefs, head of ZAMG climate research. In any case, the near-term forecast of the ZAMG is reassuring: no severe storms are to be expected in Austria in the next few days. Although further storm lows are forming on the Atlantic, according to the current forecast, they are more likely to affect parts of Great Britain and Scandinavia.