Météo France has placed several departments on yellow alert for storms this Sunday, May 19. This is particularly the case for the departments of Hautes-Pyrénées, Gers, Haute-Garonne and Pyrénées-Atlantiques.
Conditions remain stormy across most of the country. Météo France has placed several departments on yellow alert for storms including Hautes-Pyrénées, Gers, Haute-Garonne and Pyrénées-Atlantiques.
Thunderstorms may cause significant amounts of rain locally in one to two hours. Even if a move to orange vigilance is not envisaged at this stage, it is advisable to keep informed of developments in the situation, particularly in the departments currently on orange “flood” vigilance (Bas-Rhin and Moselle). where stormy rains will occur on saturated or even flooded soils, and also in the South-West where locally strong thunderstorms are possible.
Météo France’s weather report
This Sunday morning, we note the presence of numerous gray areas over a large northern part of the country. As the hours pass, from Brittany to the north of the Loire to the Grand-Est, clearings take shape but are interspersed with showers.
Stormy showers coming from Spain have been reaching the departments of Pyrénées-Atlantiques and Hautes-Pyrénées since late this night and are progressing rapidly.
The sun dominates Rhône-Alpes-Auvergne, eastern Occitanie, the PACA region and Corsica. In the afternoon, beautiful clearings appear from the Normandy coast to Nord-Pas de Calais. Further south, with the exception of the Roussillon plain towards the lower Rhône valley and the Côte d’Azur where the weather remains dry, instability becomes widespread. Thunderstorms break out almost everywhere, from Brittany to Île de France and the Grand-Est, in Aquitaine and Midi-Pyrénées where these storms become more virulent in the second part of the afternoon/evening from Spain .
Hail falls are locally possible in Midi-Pyrénées
Hail falls are locally possible in Midi-Pyrénées. The rain-snow limit is then located around 2400 m. In the evening and during the night, the storms are less virulent but the showers persist, particularly in New Aquitaine. Maritime entrances are established from Roussillon to the Rhône delta. Elsewhere, beautiful clearings dominate, conducive to the formation of mist and fog. Maximum temperatures are between 17 and 21 degrees in the northern third of the country, between 21 and 23 further south, locally 24 to 26 degrees near the Mediterranean.
What is a thunderstorm?
A thunderstorm is an atmospheric phenomenon characterized by lightning and thunder. It is always linked to the presence of a cumulonimbus type cloud, also called a thunderstorm cloud, and is often accompanied by a set of violent phenomena: gusts of wind, intense rain, sometimes hail, waterspout and tornado.
The cumulonimbus is a cloud with a diameter of 5 to 10 km, very developed vertically, which can rise up to 16 km in altitude. At its summit, the cumulonimbus spreads out widely, which gives it its general anvil shape.
A storm can always be dangerous at a given point, due to the power of the phenomena it produces.
The storm is generally a short-lived phenomenon, lasting a few tens of minutes to a few hours. It can be isolated (storm near reliefs or caused by warming of the ground in summer) or organized in a line (called “squall line” by meteorologists). Under certain conditions, storms can regenerate, always in the same place, causing heavy precipitation for several hours, leading to catastrophic flooding.
Dangers
Lightning is the name given to a flash of lightning when it hits the ground. This intense electrical discharge can kill a man or an animal, burn a tree or cause fires.
The intense rains that accompany thunderstorms can cause devastating flash floods. A cumulonimbus 1 km wide by 10 km high contains 1 million liters of water.
Hail, precipitation made up of small pieces of ice, can devastate a vineyard or orchard in just a few minutes.
The wind under a cumulonimbus blows in violent gusts up to around 140 km/h and changes direction frequently. More rarely, a very devastating whirlwind, the tornado, is created under the base of the cloud.
