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Incredible Rainstorm in Southern France

By: Christopher C. Burt, 7:50 PM GMT on September 19, 2014

Incredible Rainstorm in Southern France

Torrential rainfall Tuesday through Thursday morning (September 16-18) in the Languedoc Region of southern France has resulted in flooding that has killed at least four people with two others still missing. The rainfall rates during the storm were phenomenal.

Radar shows the intense line of training thunderstorms that swept across the Gard and Herault Districts of Southern France September 16-18. This image is time stamped at 5:15 p.m. UTC on September 17. The southern borderline in the image is the Mediterranean Coastline. Image from Meteo France.

An inflow of moist air from the Mediterranean Sea resulted in a line of heavy thunderstorms that trained across the southern French districts of Gard and Herault for almost 36 hours September 16-18. The mountainous terrain of the region contributed to orographic enhancement of the rainfall and some astonishing rainfall amounts were measured. A possible new all-time 2-hour rainfall record for France of 180 mm (7.09”) was measured at Saint-Gervais-sur-Mare (Herault District) between 10 p.m. and midnight on September 16th, surpassing the previous record rainfall for a two-hour period of 178.4 mm (7.02”) at Solenzara on October 26, 1979. See the Meteo France official table of records for French two-hour time periods here. (NOTE: Short-period rainfall records for France have not been systematically kept for very long, only since the 1970s). Saint-Gervais-sur-Mare also measured 88 mm (3.46”) in just one hour (short of the national record of 111.6 mm/4.39” also set at Solenzara during the event in October 1979—see caveat about this above). Another site, Montdardier (Gard District) picked up 273 mm (10.75”) in just five hours between 4 p.m. and 9 p.m. (September 16th). This was the equivalent to what would normally fall in two months this time of the year. The modern French record for any 6-hour period is 289.4 mm/11.39”, once again at Solenzara in 1979 (the Meteo France table of record point rainfalls does not include figures for 5-hour periods).

Over the course of the entire 36-hour long storm period from Tuesady evening 8 p.m. to Thursday morning 8 a.m., a total of 468 mm (18.43”) of rainfall accumulated at Saint-Gervais-sur-Mare, the equivalent of 40% of their average annual precipitation amount. Some other totals for this same 36-hour period include:

377 mm (14.84”) at Caylar, Herault

372 mm (14.65”) at Montdardier, Gard

327 mm (12.87”) at Anduze, Gard

317 mm (12.48”) at Saint-Hippolyte du Fort, Gard

Needless to say, severe flash flooding occurred over the affected area and at least four fatalities have been reported; campers that were swept away in Lamalou-les-Bains, Herault District. Two others are missing and presumed drowned.

The campground at Lamalou-les-Bains where at least four campers were drowned on Wednesday. Debris on the bridge shows how high the river rose during the storm. Photo by Pierre Saliba.

The famous Catholic pilgrimage site, the grotto at Lourdes, was flooded and closed for the 3rd time in the past 18 months—flooding also occurred here last October and also in June 2013).

The Gave de Pau River floods the esplanade in front of the Rosary Basilica (Notre-Dame-du-Rosarie) during the flood of June 18, 2013. The site has flooded twice again since then, including this past week. Photo by Pascal Pavanl.

The city of Vigan in the hard-hit Gard District during the torrential rainstorm on Wednesday (September 17). Photo by Ophelie Garcia.

Amazing as the storm totals were, they are not close to the French national record for any 24-hour period. The greatest modern official figure for such is 633.2 mm (24.93”) at Mont Aigoual on February 24, 1964. However, much greater amounts were estimated to have fallen during a catastrophic rain and flood event on October 17, 1940. The war had disrupted the French meteorological service at that time, so it was difficult to garner accurate information about the rain totals but 840 mm (33.07”) in 24 hours was reportedly measured at the power plant in Llau District (which borders Spain) and 1000 mm (39.37”) was estimated to have fallen in 24 hours at the nearby town of Saint-Laurent-de-Cerdans. An account of this storm can found on the Meteo France web site.

Christopher C. Burt
Weather Historian

Extreme Weather Precipitation Records

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.