Another blockage: after the drought, repeated rains …


For several weeks now, a vast depression system has been spreading all over Europe. This vast depression is somehow caught between a high on the North Atlantic is another anticyclone that rises from the Middle East to the Caspian Sea.

And as the simulations for the next days do not envisage real evolution, France would always be located in the wake of depressions with the possibility of gales and especially repeated rain with a risk of flooding.

Isobaric evolution on the ground and at 500 hPa valid until Monday, November 18, 2019 – GFS RUN from Wednesday, November 6 8h

Cumulus precipitation forecast until Monday, November 18, 2019 – GFS RUN Wednesday, November 6 8am

It seems even on longer-term models that this low-pressure (and therefore very humid) ocean current would persist for much of winter and perhaps beyond … (let's be very careful …).

Simulated rainfall anomalies for November and December 2019 (wet = green and mostly blue)

Simulated precipitation anomalies for January and February 2020 (wet = green and mostly blue)


Of course, all the excesses of our climate are too often attributed to global warming (now the "cream pie" of weather reports in recent years). But something new is happening a priori. To simplify: the equilibrium of the climate of the planet is done by an alternation of hot and cold. These areas of different air masses are delimited by a powerful current of altitude, the "jet stream". This jet stream moves like a snake through the temperate latitudes of the northern and southern hemispheres. But, in recent years, some scientific studies have shown that global warming can disrupt its circulation. Through the effect of communicating vessels, hot air rising more and more powerful create more and more pronounced meanders and thus situations of blockages. For example, Western Europe can be in an area of ​​high pressure for weeks with drought, excessive sunshine, and then in an endless low-pressure corridor with rains, storms and floods. There has also been a resurgence of cold drops that descend to lower and lower latitudes, resulting in snowfall in regions that are not used to it.

Diagram made by Thibaud Sechet for the book Extreme Weather >>

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