CLIMATE CRISIS

What is causing the Biblical deluge in Central Europe?

Central Europe has just seen off-the-scale amounts of rainfall that has flooded cities across the region in an unprecedented extreme weather event. The combination of the hottest summer on record and freezing cold air swirling out of the Arctic created a lethal weather bomb that has just detonated. / bne IntelliNews

By Ben Aris in Berlin September 16, 2024

Central Europe is underwater as it grapples with a Biblical deluge, with record rainfall smashing all records and across countries in what experts are calling a “historic flood event.”

And this torrential downpour didn’t come out of the blue; meteorologists had predicted the disaster days in advance, with weather models flagging an extreme combination of variables leading to severe flooding.

As bne IntelliNews reported in February, torrential rainfall is one of the consequences of the accelerating Climate Crisis. The cause of the flooding has its roots in this year’s hottest summer on record. That has heated both the Mediterranean and the Black Sea to the temperature of bathwater. (video)

That abruptly changed on September 11 when very cold air started pouring out of the Arctic, covering northern Europe and spreading as far south as the Mediterranean and into the Black Sea, where it got trapped by a ridge of high pressure over southern Europe. (video)

Adding to the complexity of the weather pattern, a surge of atmospheric moisture originating from the Black Sea, which is significantly warmer than usual and has created the conditions for a perfect storm of cold, heat and moisture.

“This plunge of cold was part of a cyclonic wave break, essentially cutting off a low-pressure system from the main background flow,” says Scottish meteorologist  Scott Duncan, who posted a series of simulations on social media. “This means a low pressure (storm) can get trapped and sit in the same place for days.”

Duncan added that the situation has been exacerbated by high-pressure systems lingering in the region, effectively trapping the storm over Central Europe. “We should never forget about the proximity of the high pressures. They are really crucial players holding this weather event over Central Europe,” he said.

Austria has been among the worst-hit, with rainfall records shattered across the country, while the higher altitudes have seen heavy snowfall, unseasonably early.

“The rain is still falling, but we already know Austria’s rainfall records are being pulverised,” Duncan said, as torrential rain continues to cause widespread flooding and disruption. In the centre of Vienna the normally placid River Danube has become a torrent of white water barely restrained between its banks as it rages through the city centre.

Austria has been especially hard hit due to “orographic enhancement,” a process where air pushed up the side of a mountain has its moisture squeezed out of it like a sponge, intensifying the rainfall.

“Rain (or snow) events can get an extra kick when there are mountains involved,” Duncan explains.

While the immediate focus remains on managing the flood’s impacts, the scale of the disaster has set alarm bells ringing as this weather event is off the scales. Central Europe has never recorded such extreme weather like this before – not just in September, but for any month of the year.

Rain fall was concentrated in Central Europe