Will it snow? Will it not snow? Why the weather forecasts differ on the weather in Paris on Thursday

Any meteorologist will tell you: snow is the most difficult phenomenon to predict. This particularly applies to the Paris region, for which certain weather sites and applications (Google, Apple, etc.) predict a risk of snowflakes on Thursday. But what is it really? Should children already be preparing for their first snowman of the year? Not so sure…

For it to snow, there must be a combination of rain and low temperatures, below 0°C (or barely above). Thursday, the Paris region could be affected. Several weather models, such as the French Arpège and the British Ukmo, anticipate 1 to 3 cm of snow precipitation in the capital and its suburbs.

The fact remains that a model does not make a forecast and that three days before the deadline, this data is itself still uncertain. Furthermore, the “forecasts” from Google and Apple are not as precise and “reworked” as those from Météo France and the Météo Chaîne, which – to date – do not foresee snow on Thursday in Paris.

“There are many parameters that come into play when forecasting snow in the plains. The looming snow conflict can still move by 100 km by Thursday, and it will be either rain, or snow, or cold but dry,” tells us Sébastien Brana, administrator of the Infoclimat site.

Now let's assume that snowflakes will fall from the sky. The main difficulty, when we talk about snow, is to anticipate its possible hold on the ground. “The easiest case for us is the very cold mountainous area, with frozen ground or already covered with snow. On the other hand, it becomes much more difficult for the plains when the air close to the ground is at 0°C. At this temperature, water can easily and quickly go from the liquid state to the solid state, and vice versa,” François Gourand, forecasting engineer at Météo France, told us in 2022.

Ground handling is particularly difficult to anticipate in the Paris region. And Sébastien Brana clarifies: “The temperature of the roadway is linked to the conditions of temperature, humidity and sunshine (even weak) during the preceding hours… In short, it's very complicated! »