Through king crepentmeteorologist
Posted 04/10/21, updated 04/13/21 at 1:48 p.m.-
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After the episode of severe frosts last week with catastrophic consequences for fruit trees, vines and crops, new frosts are occurring this week. They are less severe but occur daily with a higher level of humidity in the air which raises fears of further damage.
This Tuesday: still many frosts until in the southwest with locally -4 ° C
This Tuesday at dawn, the frosts affected about 60% of the territory. The lowest temperatures concerned Normandy, Hauts-de-France, Ardennes and Auvergne with -3.1 ° C in Caen, -4.2 ° C in Beauvais (60) and Valenciennes (59), – 4.5 ° C in Charleville-Mézières (08), -5.3 ° C in Montluçon (03). Note that the frost did not spare the Normandy and Picardy coastlines with -1.2 ° C in Deauville (14), -2.2 ° C in Dieppe (76) and down to -3.1 ° C in Cayeux-sur-mer (80)
In the southwest, it is often the coldest April 13 since the opening of weather stations. This is the case in Mont-de-Marsan (40) with -2 ° C, Agen (47) with -2.1 ° C and Auch (32) with -2.4 ° C. Locally, the mercury fell to -4.7 ° C in the Lot at Blars.
This Monday: the frost affected a small northern half of the country with -4 ° C in Sologne and the Ardennes
As expected, behind a disturbance that crossed France over the weekend, the sky cleared overnight from Sunday to Monday. With the arrival of a mass of cold air from high latitudes, temperatures dropped. Frosts were observed over 40% of the territory this Monday morning with -1 ° C in Chartres, Pontoise and Rennes, -2 ° C in Vannes, Nantes, Troyes and Reims, -3 ° C in Beauvais and Blois and up to -4.6 ° C in Charleville-Mézières and -4.7 ° C in Romorantin.
Frosts almost every morning
Thus, it will freeze every morning until Thursday in two thirds of France. The only small exceptions: a small south-western fringe of the country and the Mediterranean coast. For the lower Rhône valley, the maintenance of the wind, although weakening markedly from Wednesday morning, should limit the risk of frost, but the Provençal interior will often be windy from Wednesday morning, between Manosque, Apt, Aix-en- Provence and the interior of the Var, it could suffer frosts of -1 ° to -4 ° C.
Less severe frosts but high air humidity
Compared to last week, the air mass is less cold: the accumulation of cold air on the ground is therefore less important. But clear nights promote nocturnal radiation, that is to say the loss of heat to space: frosts will therefore be inevitable but they will be less severe. On the other hand, the humidity level in the air is higher than last week in connection with the recent precipitation of the weekend. With a temperature level higher than last week, the damage can be comparable for some crops sensitive to frost.
Reliability to be confirmed on the intensity of the frosts
It seems certain that the frost will be less marked than last week. However, peaks between -3 ° C and -5 ° C in the plains may occur in the first part of the week in areas most exposed to the cold such as valley bottoms or certain regions with a particular substrate (Sologne, Landes forests or of Fontainebleau due to the sandy soils) .This situation will have to be refined day after day. But at first, the following scenario seems to emerge:
– Wednesday: the frost will be marked from Normandy to the Ardennes as well as from the center to the east (-2 to -4 ° C) and generally 0 to -2 ° C from Brittany to Ile-de-France and in descending towards the interior of the southwest. Temperatures may again drop to between -10 ° and -15 ° C in the high-altitude stations, which is remarkable but of no consequence for the vegetation, which is still dormant up there.
– Thursday: the risk of frost will still concern two thirds of the country with -4 ° C to -2 ° C from Auvergne to Lorraine and 0 to -2 ° C from the north-west to the Paris Basin. The frosts should spare the southwestern plains.
– Friday: the risk of frost should decline to affect Normandy and the regions from the north-east to the center-east.
In conclusion, the agricultural sector will still be put to the test in the coming days, even if the Major damage has taken place this week. It will be advisable to protect what can be, while noting that these jellies will be all the same less harsh.
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