Where is the drought in France in early November? 03/11/2022

A drought still present in France:

The riots returned to France in early November with more disturbed but also rainier weather. However, the drought situation in our country remains worrying.

Indeed, the month of October was drier than normal throughout France with a particularly marked lack of rainfall in the south of the country. The ratio of monthly rainfall to the average reaches approximately 20% of the monthly average (1991-2020) from Aquitaine to the south of the Alps, 30 to 40% near the Massif-Central and between 40 and 50% from the Pays de la Loire to the north.

Only the regions from the center to the north-east and from the Rhone valley to the north of the Alps fared better thanks in particular to a a succession of unusually active thunderstorms for the period.

Ratio with the aggregate average monthly rainfall on France during the month of October 2022 – Weather France

Therefore, the average monthly total reaches 58 mm in the country for this month of October 2022, or a 37% deficit than normal. October 2022 then becomes the 8th month of the year with a rainfall deficit after a slight excess in Septembera dry trend that has therefore largely dominated since the beginning of 2022.

Ratio with respect to the reference standard (1991-2020) of the aggregate monthly totals of precipitation in France during the year 2022 – Weather France

This persistent water shortage is also visible in the number of drought decrees that are still particularly important for this time of year. From 31 October almost the entire country was subject to water restriction orders (some departments have not been updated) with a persistent crisis situation over a large western and southern half France where rainfall has been very scarce in recent weeks. However, the situation has improved where October rains were more frequent, although water levels generally remain low in early November.

Water restriction orders in France as of 31 October 2022 – Propuvia

While the rains of early November and thunderstorms in October significantly improved the drought of the surface soils, the situation often remains deeply problematic. Since 1 October, a large number of groundwater tables in France have seen their level drop and the particularly dry month of October further aggravated this situationespecially in the south and west of the country. However, these levels started to rise again in parts of the north and north-east thanks to the frequent thunderstorms in October.

Groundwater status in France on 1 October 2022 –BRGM

The situation is particularly worrying in a part of south-eastern and central-western France where water shortages are very marked.

In the Var 28,000 inhabitants of the Pays de Fayence, for example, have the obligation not to exceed 100 liters of water consumption per day and per personGroundwater levels in the region and in Lake Saint-Cassien, the industry’s main water reserve, were abnormally low for the period. Some neighborhoods were also supplied by tankers, and have been for several months.

Lake Saint-Cassien in the Var has a water level 7 m lower than normal – France 3 Regions

On the side of the Tarn, almost 45,000 inhabitants in the south of the department risk being deprived of drinking water by the end of the month if the situation does not improve there, too, water supplies were at historically low levels in early November.

The water level of Lac des Saint-Peyres in the Tarn is currently particularly low – Photography: Carole Pélissier

The drought is therefore contrasting in early November in France with a situation that remains worrying in many sectors of the West and South of France, but slightly improving in the North and part of the Center-East.

Beneficial but insufficient rains this week:

After a very dry and hot October, the situation became more disturbed at the beginning of November with the return of conditions of low pressure and above all rain over a large part of France. In fact, the interruptions will continue until next week, affecting almost the entire country.

The animation of the rainfall totals in the 24 hours from 3 to 10 November 2022 – GFS model via WX CHARTS

The stacks are announced more pronounced in the north-west of the country and around the Alps but still insignificant in a part of southern France where the recurrence of the lack of rainfall remains very worrying.

Total rainfall expected from 3 to 10 November 2022 – GFS model via WX CHARTS

This precipitation will therefore still be insufficient in much of southern France to stop the persistent drought for many months. If the soils can be temporarily moistened, the lack of significant accumulations will not guarantee an improvement in groundwater reserves.

On a part of the north-west and near the Alps these rains are announced more frequent and potentially more pronounced. These will then be more likely to significantly improve the situation despite the overall deficit is still too high for the drought to completely disappear.

Time might as well they will dry up significantly over France again after this period more disturbed due to a rapid return of high pressures from the Atlantic. These high pressures could in fact still focus on France, guaranteeing calm and above all very dry weather starting from the middle of next week.

Animation of geopotentials at 500 hPa in Europe from 7 to 11 November 2022 – GFS model via WX CHARTS

This dry trend would also persist for the rest of the month according to some scenarios, giving rise to fears of a new accentuation of the drought in our country.

Will winter be rainier?

The charging season it generally extends between September and March in France. It is during this period that groundwater supplies generally return to satisfactory levels before the summer season, which is generally much drier.

After an autumn for the moment in deficit due to a general lack of water since the beginning of the year, it will be important that the winter is humid in our regions, especially in the south and west where the lack of water is more marked.

The European model predicts a winter generally within the standards in France and also potentially quite arid in the north of the country (especially in the Northeast between December and January). The only positive precipitation anomalies were observed in the Southeast where rainfall could be more recurrent than usual, which would be excellent news for these sectors.

Precipitation anomalies during winter 2022/2023 in Europe –ECMWF

On the American model side, the trend is quite similar with all the same a more marked dry trend in France and in particular from the South-West to the North-East. A situation that could prove to be problematic after a year that is already not very rainy, even after a winter 2021/2022 that is too dry.

Precipitation anomalies during winter 2022/2023 in Europe – American model CFS

If these seasonal trends persist to be taken with tweezersthe situation should be carefully monitored, a recurring lack of rainfall that could be very worrying to start the year 2023.

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