A blizzard and bitter cold in the north, freezing rain in the center and spring-like foehn in the south, means Germany is in for a weekend of weather extremes. Meteorologists are already talking about a "memorable event with rarity value" - and are drawing comparisons to the winter of 1978/79, when a snow catastrophe in northern Germany caused the transport, supply and communications network to collapse.

Experts expect a temperature differential of about 20 degrees between northern and southern Germany. "Something like this doesn't happen every day," said DWD meteorologist Sebastian Altnau.

Weather phenomenon:
The cause of the rare weather phenomenon is, on the one hand, the low-pressure area "Tristan" lying over Gibraltar, which lets a powerful gush of humid-mild air flow into the south. On the other hand, there is high air pressure from the North Sea to eastern Central Europe. This causes extremely cold air from the polar region to flow directly into northern Germany. This brings the northeast and north to temperatures of minus 15 degrees, as the DWD predicted.

DWD spokesman Andreas Friedrich referred to the so-called polar vortex split. Normally, this air vortex moves in a circle directly above the region of the North Pole - hence the name. The vortex regularly intensifies in winter, when no sunlight can warm the atmosphere there and it increasingly cools, which leads to a drop in pressure at altitude.

If an "outbreak" occurs, the vortex splits and can shift. "There's always an outbreak like that - but this time it's hitting us hard," Friedrich said. Thus, the cold Arctic air masses succeed in advancing far to the south, so that northern Germany is also affected.

The weather outlook for the north:
"The effects of this weather situation will be dramatic," said Franz Molé, head of the DWD's Forecast and Advisory Center. In affected areas, people should be prepared for power outages or it will be impossible to leave the house because of black ice. "It swings high starting Saturday in the second half of the day."

The north is threatened with up to 40 centimeters of new snow, plus "enormous snow drifts" due to storms. According to the DWD, the region from Emsland in Lower Saxony and Münsterland in North Rhine-Westphalia to the Harz Mountains will be particularly affected from Saturday evening. In the Ruhr area, the Siegerland region, central Hesse and Upper Franconia, on the other hand, there will be freezing rain from Sunday afternoon to Monday, which could result in a layer of ice several centimeters thick. The DWD expects significant traffic obstructions due to thunderstorm-like freezing rain and damage to nature due to ice breakage.

Traffic situation:
DWD meteorologists expect nationwide impacts on roadways and railroads. The freeway maintenance services in the north are prepared: In Schleswig-Holstein, Hamburg and northern Lower Saxony alone, they are on standby around the clock with around a hundred clearing and gritting vehicles and 250 employees to keep the approximately 750 kilometers of highway in these regions free of snow and ice over the weekend, said a spokeswoman for the northern branch of the Autobahn GmbH of the federal government.

The spokeswoman appealed to motorists to adapt their driving to the weather conditions and not to overtake snow clearing and gritting vehicles. The Brandenburg Ministry of the Interior recommended that people stay at home if possible.

Deutsche Bahn informed: "There may be delays and train cancellations." Passengers who wanted to postpone trips planned for the weekend due to the announced onset of winter in northern Germany could either use long-distance tickets already booked "flexibly or cancel them free of charge up to and including seven days after the end of the disruption."

The weather outlook for the south:
"The southern half is largely free of warnings over the weekend," the DWD forecast said. "At the edge of the Alps, stormy southerly foehn will set in temporarily, bringing highs there up to 15 degrees on Saturday." For the southwest, the weather service expected temperatures of eight to 13 degrees on the weekend.

However, some areas in the south are also plagued by bad weather. For example, a slope near Wangen in the Allgäu region slid over a length of about 80 meters on Thursday evening. This was preceded by heavy rain and melting snow. For the time being, two residential buildings were evacuated as a precaution, according to the police. No one was injured.

Floods in some regions:
Water levels remain high on some rivers, such as the Rhine. The water level in Cologne was 8.54 meters early Friday morning - about 33 centimeters more than a day earlier. But the situation was not dramatic, said Marlene Willkomm, deputy head of the flood control center in Cologne. "This is just normal winter flooding." Up to a water level of 11.30 meters, Cologne is safe, she said. On Thursday, navigation on the Rhine in Cologne had been suspended for the time being because of the high water.

There is flooding not only in the far west of Germany, but also on the Elbe River in the east - in this case due to thaw and rain in the river's Czech catchment area. "The wave is rolling," said a spokeswoman for the State Office for the Environment, Agriculture and Geology (LfULG) in Dresden. The elongated flood peak will have reached Riesa by Monday night, she said, but hydrologists do not currently expect the alert level 2 to be exceeded. "There are local restrictions, but no acute danger."