European End-of-Season Report for the Winter 2017/18

Research in the US has shown that accidents caused by icy roads account for more fatalities than all other weather-related hazards altogether. Although the situation in Europe is somewhat different, winter road maintenance services, all over Europe, have the demanding task to ensure road safety in the most economical way with the least environmental impact.

The amount of effort winter road maintenance services need to exert naturally depends on the weather conditions itself, but also on the accuracy of weather information services they consult to plan their activities. MeteoGroup has been a provider of this consultancy for many years already, and has developed several models and tools to support road services. This has resulted in an excellent forecast quality, delivered through meteorological experts in weather rooms in eight European countries. In many cases our hit rate for the prediction of the minimum road surface temperature was well above 90%. Here’s a small  recap on this past winter.

Weather Conditions 2017-2018
The winter of 2017/18 affected road services in many different ways. In most European countries it started relatively mild, had a turbulent middle and then an unusually cold finale. Noteworthy are also the record snowfall amounts seen in alpine regions, leading in part to severe flooding when the snow melted in early spring.

November and December 2017, as well as January 2018, will be recorded as warmer than climate average. The end of the last winter season however, was characterized by unusually low temperatures.

Surface air temperature anomalies summary
November and December 2017 were warmer than the 1981-2010 average over eastern Europe, and January was warmer over almost all of Europe. The most spectacular warming was observed in December over the Arctic, the monthly temperature was more than 6°C above average over parts of Svalbard. In contrary, November was cooler than average over large parts of the west of the continent and December over the south-west of the continent. January 2018 was warmer than the 1981-2010 average over almost all of Europe. It was especially warm over a belt from France eastwards and over the far north and north-east. It was cooler than average over only a few areas of the continent.

February 2018 was colder than the 1981-2010 average for the month over much of Europe. It was only warmer than average in the far north and over the south-east of the continent. The latter part of the month was characterized by the intrusion of very cold temperatures from the east, in stark contrast with daily temperatures in parts of the Arctic more than 30°C above the daily average. March 2018 was colder than the 1981-2010 average over almost all of Europe. It was only warmer than average over the far north and over the far south-east of the continent.

February

Abundant snowfall in the Alps
Several cases of cold air mass intrusion from the North, which met with much warmer humid air masses in central Europe resulted in some massive snow events. This effect was enhanced by the highest mountains of Europe in the Alps and brought record snowfall last winter.

Strong winds
January stood out due to several significant storms. In the beginning of January storm Burglind caused severe damages, especially in Germany. Then, in mid-January, a low-pressure center on the North Atlantic developed into a severe storm named Friederike, which hit the British Islands on the night of January 17/18th and continued into Germany, Benelux and Central Europe countries on the following day.

Know-How:
Sudden Stratospheric Warming, the most characteristic feature of this European winter

 


Each winter, as polar latitudes receive little or no sunlight, the air in the stratosphere above the Pole cools rapidly and a strong westerly wind flow develops around this ‘cold pool’. This is called the polar vortex. However, the natural variability and fluctuations in surface weather across the globe can sometimes generate large vertically moving waves in the atmosphere. As these waves travel up towards the stratosphere they tend to increase in strength and can sometimes act to slow down the polar vortex, rather like a brake being applied to a fastmoving wheel. If the waves are strong enough, then the westerly vortex can distort and even break down completely, with the wind direction reversing and becoming easterly. This change in wind direction is also accompanied by a rapid rise in temperature in the stratosphere, called a sudden stratospheric warming (SSW). SSWs tend to occur about once every 2 or 3 winters, normally between mid-January and mid-March. After a strong SSW, the weather patterns over Europe can become more conducive to allowing colder wind flows to develop from the north and east, with high pressure over the north Atlantic, Scandinavia and Iceland blocking the mild westerly winds.

That is exactly what happened in February 2018. It caused a freezing cold end of a rainy and mild winter.

end of season report

Please click here for the full End-of Season Report with detailed information for individual countries and an evaluation of the MeteoGroup forecast quality.

 

Learn more about MeteoGroup's full Winter Maintenance Services

 

 

MeteoGroup delivered this winter an excellent forecast quality through meteorological experts in weather rooms in eight European countries. In many cases our hit rate for the prediction of the minimum road surface temperature was well above 90%.