Devastating Super-Cell Storms August 2023 Over Bavaria

August 2023 saw extreme weather events in Middle Europe. It wasn’t so many events, but a couple of significant storms. A number of super cells in Germany led to damage. There were some typical weather patterns in Upper Bavaria along the alps, where notorious hail-stripes are well-known, but the intensity of extreme weather was surprising.

One of the most significant extreme weather events happend on August 26 in the afternoon. Two supercells brought incredible amounts of hail in Southern Germany. A number of 123 places were affected, according to German Weather Service DVD. The separate weather systems rolling over Bavaria with a distance of 100 km. The two super-cells left a trail of destruction at a length of 130 km. The strip of hail had a width of 15 km. In that zone there was a lot of destruction in Benediktbeuern with a well-know monastery and Bad Bayersoyen. In some places hail had diameters more then 5cm, which turns them into bullets with high speed. Between the strips there was no such destruction but strong gusts of wind. The maps of the Europan Severe Weather Database deliver an impression of the two trails of destruction.

Heavy Thunderstorm on August 13 with intense lightning

Before these events, there were also heavy thunderstorms on August 13. These storms were coming from Baden-Wurttemburg. The video on the Youtube Channel shows how the storm quickly intensifies. There was also a remarkable amount of lightning. The immense rate of lightning lit the sky and lasted unusually long.

There are no fundamental new weather patterns here, but what happened is what climate-researchers predicted a long time ago. A hotter and wetter atmosphere contains more energy. This energy is a precondition for stronger storms as these super-cells. And it is not only a warmer atmosphere. Early this year, researchers detected unusual warm surface temperatures in the oceans for example the atlantic ocean near Florida.

Here is the development of the thunderstorm in the early evening hours of August 13 in Upper Bavaria, close to lake Ammersee:

The late sun illuminates towering thunderstorm clouds

At first sight the huge tower of clouds looked  impressive but not as monstrous it became.

There was an incredible dynamic in the chaotic atmosphere

Within minutes the sky changes and dark clouds approached fast. In the upper half a rotating pattern appeared.

Lighting strikes came close very fast and a huge curtain with fall stripes appeared.

This storm brought intense rain and hail in some places. Later there was intense lightning.

The supercell storms on August 26 seen from a ship on a lake

There had been further dramatic weather events after August 13. On August 17 a monster thunderstorm set parts of Nuremberg in Northern Bavaria under water after a flash flood. The series of severe weather peaked on August 26 with the two super cells in Southern Bavaria and also dangerous thunderstorms in between. The pictures below were taken on a ship on Lake Ammersee. Here it was very hot and the sky was clear til middle of the afternoon. Then, dark clouds were arriving very fast. The orange flashing lights on the storm warning lights were activated. It was important that sailors headed back to harbour in time because the line of thunderstorms arrived fast with strong winds and rainfall later.

An unusual sight

Weather is always unique. Compared to the previous thunderstorms, the sky “looked” more like it was typical rain clouds. However these was a severe weather system at any place. The wind picked up very fast and the normally peaceful lake turned into a raging water with remarkable waves. Strong rainfall let the shore disappear in a sort of mist minutes after the wind gusts appeared. Later the evening, the weather calmed down. However the damage in many regions was dramatic.

Dark clouds approaching from South-West

The clouds quickly become darker.

Still some sunshine in the Alps before the super cell system arrives

It’s getting pretty dark even during the afternoon.

Gusts of storm at the westside of Lake Ammersee in Bavaria. A motor boat makes it barely into the harbour.

What came after the storm

The super cell weather systems were the harbingers of more extreme weather in the alps. The days later there was heavy rain and a flood created more damage in Austria. On August 28 the famous Oetztal was cut off from the outer world after a mudslide destroyed the only road. Many tourists could only leave via the Timmelsjoch mountain pass. Helicopter’s brought food and other stuff into the valley.

Only days later a high pressure system brought calm and unusually warm weather in September. The super cell storms and the following devastating floods were dire reminders what living in a new climate triggered by climate change means. It means coping with a different world, less comfortable, more unpredictable and more violent. August 2023 was also one of the hottest summers on record.

June 2019: Dramatic Hailstorm put sailors in danger and a monster Heatwave.

May 2019 was the first month in Middle Europe for a long time which wasn’t too hot. There were some rainy days. It seemed that weather might turn in a more “normal” mode compared to 2018. This was before June. In the larger Munich area people experienced a freak hail storm on Whit Monday. There was also severe weather in other parts of Germany in the first half of June. Later the month, large parts of Europe suffered from one of the most extreme heatwaves ever recorded.

Aftermath of severe Hailstorm in Munich region

Thunderstorms and severe weather didn’t came unexpected on pentecost. Weather models showed a highly likelyhood for thunderstorms in the Alps and the Upper Bavaria region. However the events on June 10 proved again how tricky severe weather developments can be and how difficult it is to set precicely the right weather alert in motion.

Sunday, June 9, was more or less a qiet day. It was getting warmer in Upper Bavaria and other regions. There were already weather warnings issued. On Monday, June 10, the alert system of the huge lake Ammersee south-west of Munich was activated in the morning hours, but then it was quiet for most of the day. A lot of tourists enjoyed the holiday in Germany. People were swimming and sailing. Weather forecasters and and the lifeguard service were still expecting something to happen.

The weather radar showed signals getting stronger in the Allgäu and the Upland before the Alps around Kempten after noon. Here an incredibly strong cell was building up. When I checked the radar a couple of times in the early afternoon however, I couldn’t figure out which path that storm would take. I also didn’t figured out how fast this monsterstorm would move eastwards, so I was also surprised when it suddenly became really dark on this summer afternoon.

It was around 16.23pm when the orange alarm lights at the Bavarian lakes were activated again. There were still a lot of sailors out there. At one lake the lifeguard service warned people who were still swimming in the “Wörthsee” and closed the shore. 50 minutes later all hell brake loose on lake Ammersee. The Starnberger Merkur Newspaper later published a very interesting coverage.

Alex Beck, a sailor, told later the Merkur-reporters that the storm-cell was “racing”. Very soon the lifeguard service had to solve hands full over the next hours.

The same applied to firestarters and police: The thunderstorm left a path of destruction beginning in the Allgäu, hit several communities around the North side of the lake Ammersee region and also hit the west and the north of the Munich area.

Hailstorms in Upper Bavaria are not unusual. There is particularly a history for severe weather in May and around Pentecoste. What’s so unusual was the path, which was hard to predict. Big hail is often more seen in the South-East were there is even a special cloudseeding flyer unit for this problem. I didn’t find any report from a professional weather researcher, but I am sure this was a strong super-cell. Super-cells are more likely to take unusual paths.

The intensity was the other unusual fact. I experienced also strong wind gusts and smaller hail but 10 km to the north it was raining hailstones with the size of tennis balls.

Within minutes roofs very destroyed, nameless cars damaged, a motorway tunnel was set under water, greenhouses were completely destroyed and also a grocery store. It ended up in estimated damage cost of 30 Mio. Euros.

The same time people on the lake Ammersee were struggling for their lives. A couple hung on their capsized sailing boat, others were stranded and another sailor couple were only safed by their “persenning”, a cover, from the hail bombardement. They had reached a buoy but couldn’t leave their ship. Then they had to wait out the storm. At this time they experienced waves like never before according the their account in the “Starnberger Merkur” newspaper.

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Another thunderstorm in June

The following weeks people began to recover from the hailstorm, settling insurance matters and repairing windows, cars and houses. There were more thunderstorms but nothing like the cell on June 10. However another extreme weather situation was already throwing a shadow.

Weather models predicted an enormorous heatwave for the second half of June. Weather services were astonished by themselves about the numbers. And the models were mostly right. Germany saw new temperature records but not the 40 degrees Celsius. Nevertheless, there were set many new records. It didn’t took long and the bushfires, which were a problem in May started, again.

France saw the worst with some over 40 degree Celsius records. The authorities had to issue a state of emergency in some areas. Particularly Southern France was affected.

The situation calmed by the end of month. On July 1, 2019, a cold front with thunderstorms reached Southern Germany. There are still wildfires raging. The heatwave is only part of a problem which has the potential to become the real big threat for the near future: In wide parts of Germany there is still a drought. The government published recently a study about the effects of a drought lasting several years.

cold front and thunderstorms July 1, 2019

Juni 2019: Hagelunwetter gefährdet Segler und eine Monster-Hitzewelle

Von Peter Engelmann, 4.7. 2019

Der Mai 2019 war nach langer Zeit der erste Monat in Mitteleuropa, der nicht zu warm ausfiel. Es gab auch mehrere regnerische Tage. Es schien, as ob sich das Wetter im Vergleich zu 2018 normalisieren würde. Das war vor dem Juni. Am Pfingstmontag erlebten die Menschen im Raum München ein extremes Hagelunwetter. Auch anderswo gab es Unwetter. Später folgte eine der extremsten Hitzewellen, die je in Europa verzeichnet wurden.

Aftermath of severe Hailstorm in Munich region

Die Gewitter und Unwetter kamen nicht unvorhergesehen an Pfingsten. Die Wettermodelle zeigten für die Alpen und Oberbayern schon Tage zuvor eine hohe Wahrscheinlichkeit für unwetterartige Gewitter. Doch die Ereignisse am 10 Juni bewiesen einmal wieder wie schwer es ist, eine präzise Warnung herauszugeben. Die Wetterentwicklung bleibt in ihren Details oft unberechenbar.

Der Pfingstsonntag, 9. Juni, war ein mehr oder minder ruhiger Tag. In Oberbayern und anderen Regionen wurde es wärmer. Die Wetterdienste veröffentlichten Warnungen für den nächsten Tag. Am Montag, den 10. Juni, war bereits um 7.00 das Alarmsystem am Ammersee in Oberbayern aktiv. Doch für die meiste Zeit des Tages blieb es ruhig. Eine Menge Touristen genossen den Feiertag. Viele Segelboote waren unterwegs, die Strände voller Badegäste. Die Wasserwacht und die Wetterdienste erwarteten aber, das noch etwas geschehen würde.

Das Wetterradar zeigte stärker werdende Signale im Allgäu in der Umgebung von Kempten nach Mittag. Hier entwickelte sich eine unglaublich starke Gewitterzelle. Als ich selbst mehrmals die Radarbilder betrachtete, konnte ich aber nicht vorhersehen, in genau welche Richtung das zieht und vor allem wie schnell dieser Sturm ostwärts vorankommen würde. So war ich auch überrascht, als es an diesem späten Sommernachmittag sehr dunkel wurde.

Um 16.23 wurden die orangenen Alarmlichter an den Bayerischen Seen wieder aktiviert. Zu diesem Zeitpunkt befanden sich noch zahlreiche Segelboote auf dem Wasser. Am Wörthsee warnte die Wasserwacht die Badegäste und der Strand wurde geräumt. 50 Minuten später brach am Ammersee die Hölle los. Der Starnberger Merkur berichtete davon in einer packenden Reportage.

Alex Beck, ein Segler, berichtete den Merkurreportern, dass der Gewittersturm regelrecht herangerast sei. Bald darauf hatte die Wasserwacht alle Hände voll zu tun.

Das Gleiche galt für die Feuerwehr und die Polizei: Das Hagelunwetter hinterließ eine Schneiße der Zerstörung. Diese begann im Allgäu, traf einige Orte im Norden der Ammerseeregion, aber auch der westliche und nördliche Raum Münchens war betroffen.

Hagelstürme sind in Oberbayern eigentlich nicht ungewöhnlich. Es gibt sogar eine ausgesprochene Historie für Mai- und Pfingstunwetter. Was so überraschend war, war der Pfad, der schwer vorherzusehen war. Großen Hagel erlebt man häufiger im Südosten Oberbayerns, wo es sogar eine spezielle Hagelflieger-Gruppe gibt. Ich fand keine Hinweise von Meteorologen darüber, aber ich bin mir sicher, dass dies eine Superzelle war. Superzellen tendieren stärker zu unberechenbaren Zugbahnen.

Die Intensität und die Ausdauer des Unwetter war der andere ungewöhnliche Faktor. Ich habe selber starke Windböen und kleineren Hagel an diesem Tage beobachten können (siehe Video). Doch 10 km weiter nördlich vielen Hagelkörner mit der Größe von Tennisbällen vom Himmel.

Binnen Minuten wurden Dächer zerstört, zahllose Autos beschädigt, ein Autobahntunnel unter Wasser gesetzt, ein Supermarkt dauerhaft geschädigt und Gewächshäuser völlig zerstört. Die Kosten werden auf 30 Mio. Euro geschätzt.

Zur selben Zeit kämpften Menschen auf dem Ammersee ums Überleben. Ein Paar klammerte sich an sein gekentertes Segelboot, andere waren gestrandet und ein Segelpaar rettete sich nur mit Hilfe der “Persenning”, einem Schutzbezug für das Boot, vor dem Hagelbombardement. Sie hatten eine Boje erreicht, konnten aber das Schiff nicht verlassen und mussten das Ende des Sturms abwarten. In dieser Zeit erlebten sie Wellen wie nie zuvor auf dem Ammersee, wie sie dem “Starnberger Merkur” berichtet

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Another thunderstorm in June

In den folgenden Wochen begannen die Menschen sich von dem Hagelunwetter zu erholen, regelten Versicherungsangelegenheiten, reparierten Autos, Fenster und Häuser. Es gab noch mehr Gewitter aber kein vergleichbares Ereignis wie die Zelle vom 10. Juni. Doch ein weiteres Extremwetterereignis warf seine Schatten voraus.

Die Wettermodelle sagten für die zweite Junihälfte eine enorme Hitzewelle voraus. Selbst die Meteorologen waren überrascht über die Zahlen, die sie in den Modellläufen fanden. Saharahitze sollte ihren Weg direkt nach Europa finden. Zum Großteil behielten diese Modelle Recht. Zwar wurde in Deutschland nicht die 40 Grad Marke geknackt. Nichtsdestotrotz gab es viele Extreme und neue Allzeit-Temperaturrekorde. Es dauerte nicht lange, bis Waldbrände, die schon im Frühjahr ein Problem waren, wieder aufloderten.

Frankreich erlebte die schlimmsten Seiten der Hitzewelle mit deutlich über 40 Grad und neuen Rekorden seit Beginn der Wetteraufzeichnungen. Die Regierung musste den Notstand verhängen. Besonders Südfrankreich war betroffen.

Die Situation beruhigte sich zum Monatsende. Am ersten Juli überquerte eine Kaltfront Süddeutschland mit Gewittern. Immer noch gibt es im Norden Deutschlands Waldbrände. Die Hitzewelle war nur Teil eines Problems, das das Potenzial zur größten Bedrohung in naher Zukunft hat: In weiten Teilen Deutschlands herrscht immer noch Dürre. Gerade eben hat die Regierung eine Studie veröffentlicht, was passieren könnte, wenn es zu einer mehrjährigen Dürreperiode kommen wird.

cold front and thunderstorms July 1, 2019