In movies, Christmas and snow belong together. But the chance that the two will also come together in the Netherlands is not that great.
The map below, recently made by Dominic Royé, climate researcher at the University of Santiago de Compostello, illustrates this nicely. The map shows for all of Europe how big the chance of a white Christmas is from a climatic point of view.
How likely is white Christmas in Europe? 🎄☃️❄️
I estimated the climatic chance of snow on Christmas Eve in Europe based on ERA5-Land with snow depth greater than 1 cm. #dataviz #rspatial pic.twitter.com/CwVpz8XYjw— Dr. Dominic Royé (@dr_xeo) Dec 10, 2021
And where in the east and north of Europe, climatically speaking, people are almost guaranteed to be treated to a snow cover of more than 1 centimeter thick, the chance that we in the Netherlands will be able to get the sled from the attic is a lot smaller. The east and north of our country turns a slightly lighter purple than the west and south. But the odds do not exceed 25 percent nationwide.
To create the map, Royé looked at data collected between 1981 and 2020. He looked at how often a certain area could count on more than 1 centimeter of snow on December 24 and/or 25 during that period. And then he calculated based on that how great the chance of a white Christmas is from a climatic point of view.
And then the history on which the probability calculation is based turns out to be mercilessly hard for Dutch people who fervently hope for a white Christmas. From a climatological point of view, the chance of snow on December 24 and 25 is not that great. The card is by no means surprising, says Royé. “The results are geographically consistent and reflect the physiographic and climatic zones of Europe. If you look at the chance of frost (see map below, ed.) you will see the same picture emerge. The main factors that influence this are the elevation of an area, the latitude and the distance to the sea.”
‘Winter is coming’. New smoothed frost day probability (minimum temperature < 0ºC) through the year for Europe. #rstats #rspatial #ggplot2 #dataviz pic.twitter.com/m79dfV5Y69
— Dr. Dominic Royé (@dr_xeo) October 18, 2020
When making the card, Royé did not look further at how the chance of a white Christmas has changed over time. But when asked, he says that the chance of a white Christmas is not exactly increasing. “In general, we see a negative trend in the number of days with frost.”
Even rarer
And in the Netherlands too, the chance of snow – and with it the chance of a white Christmas – is getting smaller and smaller, the KNMI previously predicted. This is primarily due to a decrease in the number of potential snow days prompted by global warming: days when the temperature is so low that snow falls from the sky instead of rain. But not only the number of potential snow days is declining. The chance that snow will actually fall down on the remaining snow days is also smaller. And that is because a warmer climate also ensures that on days when it is cold enough for snow, the wind blows from the east more often and then carries dry, continental air with it.
The KNMI speaks of a white Christmas if a closed snow cover is measured in De Bilt on both Christmas days. And that has only happened eight times since 1901: in 1906, 1938, 1940, 1950, 1964, 1981, 2009 and 2010.
So it doesn’t look climatological rosy snow-colored. But from a meteorological point of view, we can of course always be surprised. Yet such a surprise at the moment – just a few days before Christmas – is not exactly to be expected; with an expected temperature between 4 and 7 degrees, the chance of a thick layer of snow is also very small from a meteorological point of view.
Source material:
Short interview with Dominique Royé
Image at the top of this article: Arina Krasnikova via Pexels