One storm after another in the Netherlands, what causes that?

Firefighters in The Hague clear a fallen tree after storm Ciarán last November

NOS News

  • Etienne Verschuren

    editor Online

  • Etienne Verschuren

    editor Online

Pia, Gerrit, Henk, Isha, Jocelyn: the storms have been coming together in recent months. While only one storm reached the Netherlands last storm season, there have already been seven this season. And they are often accompanied by a lot of inconvenience and damage.

The KNMI has been keeping track of severe storms in the Netherlands since 1910, with a wind force of 10 or more. It is known that they are no more common today than in the past. There have been fourteen so far this century, a frequency consistent with the last century.

Storms with wind force 9 for at least an hour are recorded but not actively analyzed. However, the KNMI expects that these storms have not increased noticeably.

Storms in the Netherlands

Storm season Number of storms Names and color codes
2019/2020 1 Ciara (ploughing)
2020/2021 4 Odette (yellow), Bella (yellow), Christoph (yellow) and Darcy (red)
2021/2022 4 Corrie (orange), Dudley (yellow), Eunice (red) and Franklin (orange)
2022/2023 1 Poly (rood)
2023/2024 7 (so far) Ciarán (orange), Elin (yellow), Pia (yellow), Gerrit (yellow), Henk (orange), Isha (orange), Jocelyn (yellow)

“We do not think that winter storms will occur more often than before,” says Peter Siegmund, climate expert at KNMI. “Climate models do not indicate a change in the strength and direction of the wind. Storms are caused by temperature differences: cold air from the Arctic meets warm air from the tropics in the atmosphere. The greater the differences, the stronger the wind.

Now those temperature differences at high altitudes in the atmosphere are increasing, but this is offset by the fact that the temperature differences at the bottom of the atmosphere are actually decreasing: the Arctic is warming more than the tropics.”

According to him, it is probably a coincidence that there are more storms this winter season and that they follow each other in quick succession. In any case, it is not a consequence of climate change, but of the location of the so-called ‘jet streams’, which occur in places where temperature differences are greatest. Such a jet stream is now near the Netherlands, resulting in stormy weather. “In Southern Europe, for example, there is not much wind at all now.”

For summer storms it’s a different story, says Siegmund. Climate change does have an influence on this. “These are often smaller storms and they do occur more often. Because clouds become even warmer than their surroundings, vertical air movements arise. There are more frequent downdrafts, as in 2021 in Leersum.”

Such a downwind took place in that village on the Utrecht ridge enormous damage On. “Those kinds of phenomena are likely to become more intense and more common due to climate change, just like the increasing amount of precipitation in the fall and winter.”

The KNMI has been providing information since 2019 names of storms, following the example of Great Britain and Ireland. Storms for which code orange or code red are issued are given a name. Sometimes this also applies to storms with code yellow, for example if a storm in Ireland and Great Britain can also lead to stormy weather here.

The purpose of using names was to “increase awareness of hazardous weather.” The idea was that storms would be easier to track via government agencies and social media.

Now that the system has been used for several years, the KNMI has seen that people are indeed responding positively to it. “It is too early to say whether the system really works and promotes safety, but polls show that people are well informed and are adjusting their behavior,” said a spokesperson. Bee Poly in Ciaran for example, almost everyone knew that the storms had names. The name Poly was spontaneously known to 84 percent of respondents, compared to 68 percent for Ciarán.

“Research in the UK shows that naming storms increases awareness of dangerous weather, gives a consistent message to the public and encourages people to take action to prevent damage and injury. When you name a storm, it remains hang better than when people hear news about ‘a storm’ every other day.”

The post first appeared on nos.nl

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