Warning for heavy rains in the Mediterranean
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From Wednesday November 24 at 5:00 p.m. to Thursday November 25 at 12:00 p.m.
Situation
This Wednesday, a depression from the Iberian Peninsula is circulating in the Mediterranean between the Balearics, the Gulf of Lions and Provence. It causes upwelling of humid and unstable air on the Mediterranean coast. In a sustained easterly flow, intense precipitation occurs for several hours on the Aude before touching the Hérault then spreading to Provence-Côte d’Azur and Corsica in the evening and night from Wednesday to Thursday.
Observation
This Wednesday
At 5.30 p.m., the area of heavy rains concerns the Hérault department while the situation is gradually improving in the Aude. Rain intensities are often close to 10 millimeters / hour. In Béziers, the cumulative rainfall over the last 24 hours has now reached 82 millimeters, the equivalent of one month of precipitation. In Narbonne, the episode is coming to an end. It fell 142 mm over the last 24 hours or nearly 2 months of rain.
At 3:00 p.m., the heaviest rains concern the north of the Aude and the western part of the Hérault. The sectors of Béziers and Narbonne are particularly affected with intensities of 8 to 10 mm / hour. Heavy rains go back up to the Montagne Noire and the Espinouse massif. Rainfall accumulations over the last 24 hours reached 112 mm in Labastide-Rouairoux (Tarn), 139 mm in Narbonne (Aude) and 167 mm in Durban-Corbières (Aude), which is the equivalent of nearly 2 months of rain on this city. Some rivers such as the Aude, Orbieu or Cesse are in flood but do not threaten to overflow. Note that some marine submersions have occurred in the Gruissan sector due to a very strong easterly swell on the exposed coast.
At 11:30 am, the rains, sometimes stormy, extended from the Gulf of Lion to the Tarn. They tend to weaken a little in intensity on the coast. The Aude remained the wettest department with accumulations reaching 156 mm since last night in Durban-Corbières and 132 mm in Leucate.
At 9 o’clock, the rains now extend from the Pyrénées-Orientales where it snows heavily from 1,500 meters to the Hérault plains and has even climbed further north towards the Tarn and the south of Aveyron and Lozère. The accumulations now reach 95 mm in Narbonne (Aude), 110 mm in Leucate (Aude) and 43 mm in Saint-Jean de Minervois (Hérault).
At 7, a line of heavy stormy rains go up from the Gulf of Lion in the direction of Aude and Hérault. The strongest precipitation is at sea where we can also observe some lightning strikes. During the last 24 hours, we noticed 43 mm in Perpignan (Pyrénées-Orientales), 79 mm in Narbonne (Aude) including 25 mm that fell between 4 and 5 a.m., 109 mm in Leucate (Aude), of which 38 mm fell between 4 and 5 a.m. and up to 147 mm in Durban-Corbières (Aude). These water clusters generally represent 3 weeks to 1 month of rain for these areas.
Tuesday
This Tuesday at 6 p.m., thunderstorms broke out on the coast of the Pyrénées-Orientales and the Aude with numerous lightning strikes. The rains were sometimes sustained, in particular in the plains of the Aude, as well as in Perpignan. Rainfall amounts remained low, 5 to 15 mm over this area, but this was only the start of the episode.
This Tuesday 5 p.m., lines of showers are set up on the coast. Lightning strikes were observed under its downpours. It fell 5.5 mm in a downpour in Leucate between 2 and 3 p.m. The east wind blows in the Gulf of Lion at up to 60 km / h. The rains will now intensify in the evening, from 8 p.m., the start time of our alert.
This Tuesday noon, the bad weather episode has not yet started. The low is currently located at 1010 hPa off Valencia in Spain. It brings heavy stormy rains to Spanish Catalonia, south of Tarragona. Snowfall occurs from 1000 to 1200 m altitude on the reliefs.
In Languedoc-Roussillon, the sky is loaded and the weather becomes unstable with a few showers.
Evolution
Tonight, the improvement is confirmed in the Aude department while the heavy rains will affect the whole of the Hérault department, locally taking on a stormy character. The east wind will blow violently on the Hérault coast with gusts of the order of 90 km / h. From 8 p.m., heavy thunderstorms will break out on the coast of Bouches-du-Rhône, Var and southern Corsica.
The next night, the often stormy rains will reach the Alpes-Maritimes and Haute-Corse departments where intensities can reach 30 to 40 mm / h under storms. Note that it will snow a lot from 1,500 meters in the Alpes-Maritimes.
Thusday, the episode of heavy rains will gradually end in the second part of the morning with the evacuation of the heaviest rains towards northern Italy.
Here are the characteristics of this Mediterranean episode, classic for this time of year :
– rainfall accumulations expected in 24 hours in the order of 80 to 150 mm (equivalent to a month and a half of rain) over a vast area of the Pyrénées-Orientales and Aude with locally up to 200 mm.
– rainfall amounts of 40 to 80 mm in the Hérault with locally 120-150 mm in the Espinouse massif.
– cumulative rainfall of 30 to 50 mm, locally 80 mm on the coast of the Côte d’Azur and up to 90 mm near the Corsican mountain.
– floods on the main watercourses but which should not cause significant overflows. The level of rivers is currently very low after a long period of summer drought, extending into early autumn.
– heavy snowfall above 1800 m on the Pyrenean massif with accumulations of snow that can exceed 1 m in the sectors most exposed to the east wind. Snowdrifts may form with the strong wind.
– strong gusts of east wind of the order of 60-70 km / h inland and 80-90 km / h on the coast.
– waves of the order of 2.5 m to 3 m on the coasts exposed to the easterly swell.
– a risk of thunderstorm especially on the coastal plain.
List of departments concerned