Winter has been very mild so far, but extreme temperature drops are already threatening in March. The reason is sudden stratospheric warming.
Winter is coming to an end, the birds are singing again and the first harbingers of spring are already appearing. The cold season in Austria was significantly warmer than normal, 1.5 degrees above average.
And light now should continue in the medium term. But soon everything can be confused, because according to the estimates of UBIMET meteorologists and the UWZ severe weather center, new cold shocks may be imminent in March. The reason for this is the sudden stratospheric warming over the Arctic, which only occurs every two to three years.
This occurs when the stratospheric polar vortex – a large-scale winter low altitude over the Arctic with very cold air that often reaches values around -85 degrees – is heated by more than 50 degrees in a few days.
The disruption of the polar vortex has begun
The reason for this is the jet stream waves with great amplitude: they can propagate vertically into the stratosphere, where they then break up and finally dissipate, releasing a lot of heat. This process is accompanied by a displacement of the polar vortex or its splitting into two or three separate vortices.
The stratospheric polar vortex is often confused with the jet stream.UWZ / NOAA
For several days now, meteorological models have been pointing to sudden stratospheric warming, which will soon cross the important threshold. The polar vortex, which is currently already slightly displaced from its usual position, will be pushed further towards Scandinavia or Russia. This process has already started and the wind is expected to change from west to east at an altitude of about 30 km on February 15th.
Possible longer periods of cold
While an intact polar vortex holds cold air together in the north, such a disruption could lead to blasts of cold air that could hit central Europe and Austria. The result would be extreme drops in temperature.
“It is not yet possible to predict with certainty if and how this will affect the climate in Central Europe”, say the experts. “In any case, any effects occur with a delay of at least two weeks, but can last up to two months.”
In extreme cases, long-lasting cold spells are also possible, such as the cold waves in February and March 2018. However, these serious climatic consequences do not always occur. For example, the sudden stratospheric warming in January 2019 had little effect on our weather in Austria – but in North America it caused extreme frost, as the following photos from that time show.
Will the temperature drop in March?
No effects are expected for the remainder of February. In March, however, changes in flow conditions in the stratosphere can affect our weather. Blocking weather patterns are more likely, and cold polar air could push south or mild air north.
For Europe, this could mean a reversal in pressure conditions over the Atlantic and, in fact, from the beginning of March, the NAO tends to look like a negative phase. This was the last case in the first half of December 2022.
As usual, the long-term model forecast for March in Central Europe still looks subdued, but as things stand at the moment, the potential for cold air breaks in March is increasing. The last very cold average month in Austria was September 2022.
You can find the detailed weather forecast for over 50,000 locations worldwide at wetter.heute.at
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Nav-Account red, rcp Time02/13/2023, 19:46| Act: 02/13/2023, 20:14