Before it gets sunny and summery warm again on Saturday and Sunday, storms will sweep across the country, which according to ntv weather expert Björn Alexander can be tough. Especially those who discover a "greenish to bluish shimmering cloud UFO" should be careful.
ntv: In the end, heat and lightning often went hand in hand. Is that the case again?
Björn Alexander: Unfortunately, yes. Because before the beautiful weekend we still have to endure a change in the weather. Warm to hot summer air is flooding our country, which is becoming increasingly humid and therefore muggy and full of energy. At the same time, low "Tina" and low "Ulrike" are sending their foothills towards us in the form of a cold front.
What does that mean?
That the storm potential will increase again. And that doesn't just apply to us in Germany. Benelux, France and generally the Alpine region in northern Italy, Switzerland and Austria are also affected.
What dangers can be expected?
The weather computers again have heavy rain with a risk of flooding, hail and gusts of wind up to 100 kilometers per hour in the program. The risk of so-called supercells is also increased. An explosive weather situation, which - similar to parts of Austria recently - can bring rain amounts of over 100 to almost 200 liters per square meter.
What is a supercell?
This is a special type of thunderstorm. If a storm cloud has areas in which updrafts and downdrafts have formed separately, then the preliminary stage of a supercell has arisen. In the second step, the cloud begins to rotate. This strengthens the thunderstorm cell enormously and leads to the formation of a so-called mesocyclone. This can sometimes be a thunderstorm complex that extends for kilometers and also exists for a longer period of at least 30 minutes. Only then did a supercell emerge, which is visually reminiscent of a greenish to bluish shimmering cloud UFO, can bring enormous amounts of rain and in whose vicinity - with the right ingredients - even tornadoes can develop.
How is the storm situation developing in Germany?
In the evening and at night, the cold front with thunderstorms and the risk of severe weather will shift from the west to roughly the center of the state on a line from the Allgäu up to Schleswig-Holstein. On Friday during the day, the thunderstorm and severe weather line will then reach the extreme east, while it will quickly continue calmer and nicer from the west. Before that, there is a threat of heavy rain, hail and gusts of wind in the thunderstorms here in Germany.
It's getting "quieter" behind the thunderstorms - does that also apply to the weekend?
In any case. Because even if July crash-landed for the summer on its first day, it still wants to do a lot better on the first weekend. The dynamic ladies "Tina" and "Ulrike" are followed by the wonderful "Helmut" - who brings high and fair weather - with lots of sun and more pleasant summer temperatures.
July comes - June ends. How does the first month of summer go down in the weather history books?
After a rather cool start, June got off to a good start and brought us a very intense and early heat situation with new records in the second third of June. For example, with 39.3 degrees in Altdöbern or 39.2 degrees in Dresden and Cottbus. In some cases, all-time records were broken at the stations, so it has never been so hot so early. Compared to the comparative period 1961-90, it was a good three degrees too warm.
Were there also differences in the distribution of heat?
In any case. This is particularly noticeable in a north-south comparison. In some cases, the north was barely a degree warmer than the long-term average. The south, on the other hand, got a temperature surplus of more than four degrees. On average across Germany, June 2022 was the sixth warmest June since records began. At the same time, storms also repeatedly intervened, so that there was unfortunately sometimes enormous damage, but also the all-important rain. Nature has more than it needs after the dry spring.
How much rain did it fall in June 2022?
The national average is around 55 liters per square meter. This corresponds to about 2/3 of the monthly target. As a result, it was too dry overall; there were also large regional differences in the rain. It was particularly dry from northern Bavaria and Saxony up to Mecklenburg-Western Pomerania and across to the east of Lower Saxony with barely 10 liters per square meter. It was normally wet or even too wet in parts of southern Germany and at the Northern Lights.
Does July do better in the rain?
The experimental long-term trends of the American weather service NOAA actually forecast a rather wet course for July 2022 in the east. The western half, on the other hand, is expected to get through July too dry. Incidentally, the long-term average in July is usually around 80 liters per square meter.
Back to the summer comeback at the weekend: how nice will it be in Germany?
It's getting pretty nice and warm. The sun often dominates and brings us 11 to 15 hours of untroubled operation per day - although Sunday could even be the sunnier and warmer day overall. Temperatures will reach 22 to 30 degrees on Saturday and 22 to 31 degrees on Sunday. At the same time, the air stays dry and fresh, so that it cools down well at night and we can ventilate really well.
Speaking of cool, how cool are the bathing lakes promising us at the moment?
Depending on the size and depth of the water, it is often between 22 and almost 26 degrees. It is less warm in the North Sea and Baltic Sea with 18 to 22 degrees. This is measured at a depth of one meter. Accordingly, flatter bank and coastal areas can be noticeably warmer.
What trends can we expect over the next week?
Increasingly muggy again in the south on Monday and Tuesday and therefore thunderstorms. Another storm cannot be ruled out. Otherwise, the new week will be sunnier, before the rest of the country is likely to become more changeable and generally cooler from Wednesday.
How are the temperatures developing?
On Monday and Tuesday it will be 19 to 28 degrees warm. Wednesday, Thursday and Friday, on the other hand, are less and less summery with highs between 17 and 25, maybe even 26 degrees. It is still warmest on the Upper Rhine. Only at the weekend are there more signs of a sunny and warm summer comeback.