By Briac Trebert
Published in
In matters of weather report, predicting the weather for several weeks turns out to be an almost impossible mission. The question : Will winter be cold? The forecasters will answer unanimously: “it is urgent to wait”, and will evoke the notion of “probability”.
Because seasonal forecasts exist. They indicate “the most likely scenario” among three predefined scenarios: near, below or above average.
So what about this winter? The European Center for Medium-Range Weather Forecasts (ECMWF) “see nothing”, summarizes, in Actu.fr, Yann Amice, Meteorologist at SportRizer. The projections of this model do not contemplate “any particular signal” in terms of temperatures in France in the coming months. which would mean that the France is expected to experience near normal temperatures in December, January and February.
The meteorologist Guillaume Séchet’s notes on an article that it has been several years since “fall projections for next winter have not presented a neutral picture (all recent winters have looked milder than normal).”
What about the performance of seasonal forecasts?
“If it is very cold this winter and EDF delays in reopening the nuclear reactors, we will enter into exceptional measures”, Emmanuelle Wargon, president of the Energy Regulatory Commission (CRE), has already warned about the tension in electricity and gas as Winter is coming in France.
Therefore, the ECMWF forecasts may, “on paper”, cause concern.
The fact is that if “the performance of seasonal forecasts is better for temperature than for precipitation”, notes Météo France, and is better for winter than for summer, they are very difficult to take into account in Western Europe.
“Without being zero, the yields remain weak”, indicates the official service of meteorology and climatology of France. “This is due to the characteristics of the general circulation of the atmosphere over the Atlantic Ocean in temperate latitudes”, justifies Météo France.
Yann Amice also puts this “probable normality” into perspective, “especially in the face of the temperature of the Atlantic Ocean, which at the moment is still very high.” He points to the effect of climate change “increasing variability and thus potentially excesses.”
(Very) hot anomalies have given way to (slightly) cooler anomalies
What is certain at the moment is that at the beginning of autumn, the dominant flow is oriented towards the northwest sector, which brings (for the moment) a seasonal climate with temperatures generally within the normsor even a slight deficit, of the order of –0.5°C.
Therefore, the forecasts for a few weeks and a few months would give this temperature trend quite close to the seasonal averages in France.
Having been mild in France in recent years, it is therefore “plausible” to say that the next one could be “colder”. Since mid-September, the (very) hot anomalies of this scorching summer seem to have given way to (slightly) cooler anomalies. “And this, in a context in which the last five winters have been milder than normal,” says Guillaume Séchet.
We have to go back to the winter of 2012-2013 – almost 10 years ago – to find a significant thermal deficit in France.
Three of the four warmest winters have occurred in the last 10 years
In meteorology, winter includes the months of December, January and February, which is the coldest time of the year in the northern hemisphere. On average in France, the normal temperature for the season is 5.4°C. Since 1900, the winter of 1962-63 was by far the coldest, with temperatures averaging 0.7°C, or 4.7 degrees below normal.
The 2015-2016 winter turned out to be the warmest with an average temperature of 8°C, 2.6 degrees above normal. This value relegates the winter of 1989-1990 (+2 degrees) to the second place among the mildest winters since the beginning of the measurements.
Three of the four warmest winters have occurred in the last 10 years with the winters of 2006-2007 and 2013-2014 (+1.8 degrees) tied for 3me podium step.
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