This is not the idea we had of deconfinement, let’s face it: rain, a lot of rain, fell on France in June. Sometimes overwhelmingly in a short time because of the many thunderstorms that also erupted. Yet nothing deeply abnormal for a month of June. What has happened in France in recent weeks? This is partly the “fault” of a mass of air called the “cold drop”.
What is the “cold drop”?
A cold drop, or more exactly a drop of cold air, is a relatively small mass of cold air surrounded by a mass of hot air. In this month of June, some have been found, from the British Isles or the near Atlantic, to come and nest in France.
This is part of what caused the rainy and stormy weather in June. Because these “cold drops” are nestled above a mass of hot air, as the forecaster of Météo-France interviewed by 20 minutes, Jérôme Lecou: “When on the surface (the first hundreds of meters of the atmosphere), the conditions are rather warm and there is an overhanging phase of cold air ranges which circulate around 4,000 / 5,000 meters, you have an unstable profile absolutely favorable to the formation of convective clouds, cumulonimbus clouds, storm clouds. “
A cold drop will come to isolate itself and fill up very slowly over the country as the days go by. Consequences: a very gloomy weather between #humidity and #freshness for the whole of next week! pic.twitter.com/FZquaVxNm0
– Guillaume Séchet (@Meteovilles) June 26, 2021
This therefore explains the storms and of course also the rain. In the conditions of this month of June, with this superposition of air masses, really very thick clouds formed: up to 10 km from the base to the top, even affirms Météo-France. “There is therefore an extremely marked possibility of precipitation formation inside the cloud, with the possibility of hailstones”, observes Jérôme Lecou.
Is the rainy month of June exceptional?
Météo-France reminds us that the rainy and stormy months of June exist. “The French climate being a mid-latitude climate, we have a variability which is strong during the first months of summer. The month of June can have all styles: it can be very dry but also very stormy ”, describes Jérôme Lecou. However, it should be noted that it rained at a level well above normal.
“For example, we had more than double the rainfall observed on average on an axis that goes from New Aquitaine to the Paris region via the Loire Valley”, comments Jérôme Lecou. Several stations exceeded 130 mm of precipitation, the mark of “heavy rains”, according to the forecaster. In some places, such as Gonneville in La Manche, rainfall was three times the average observed in June.
Will the bad weather continue?
If you took your vacation in early July, bad news: yes, it will continue. “From this weekend, we start again on a stormy and rainy trend. There is no calm, sunny and warm weather in prospect for the first ten of July in any case, ”warns Jérôme Lecou. For the rest of the summer, of course, it is too early to tell. There is indeed the seasonal forecast “but that does not allow me to say if the third week of July will be stormy, for example”.
Yes, but a priori according to Météo-France we are still heading towards a hot summer. Except that a hot summer can mean a lot of things. Take the month of June 2020, not sure you found it hot. Especially compared to the month of June 2019, marked by an episode of heatwave. However, it has been warmer this month. “The temperature anomalies of these two months of June are quite close: in 2019 we were at +1.79 degrees and in 2021 we will not be very far from 2 degrees,” explains Jérôme Lecou. In the end, June 2021 will be in the five hottest months since the start of the surveys.