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Thursday
June 05, 2025,
10:00 UTC



 Severe thunderstorms
Southern Germany, Czechia,
Poland
04 - 05 June 2025

Visible satellite imagery
of the multiple supercells
over Central Europe,
04.06.2025 18:30 UTC,
Source: EUMETSAT View

Severe weather impacted parts of Southern Germany, Czechia, and Southwestern Poland. Ahead of an unseasonably strong low-pressure system located north of the British Isles, favorable synoptic conditions led to the formation of multiple supercells over Bavaria in the evening and nighttime hours of June 04, 2025. The supercells brought heavy downpours, locally stormy winds with gusts of more than 100 kph, and isolated large hail with diameters of 3 cm.


After a spring with well-below-average precipitation in large parts of Western and Central Europe, a surge of cold air originating from the Arctic fueled the development of an unseasonably strong low-pressure system over the Northern Atlantic in the first days of June 2025. Ahead of the low-pressure system, moist and warm air masses were advected into Central Europe. Over Germany, secondary low-pressure systems formed on June 04, 2025.

Development of the 500 hPa geopotential, 1000 hPa to 500 hPa thickness, and sea-surface pressure (first row), 850 hPa pseudo-potential temperature and sea-surface pressure (second row), mixed-layer CAPE and Lifted Index (third row), source: wetter3.de, and analyzed fronts and sea-surface pressure (fourth row), 04.06.2025 06 UTC - 05.06.2025 00 UTC, source: DWD


The cold front of a small low-pressure system located over the Northern Lowlands of Germany stalled over Western Germany. Along the front, continuous rains with embedded convective activity brought widespread precipitation totals of 15 to 30 mm in a stretch from Dijon in Eastern France over Frankfurt into the Harz Mountain range. Isolated precipitation totals of up to 50 mm were measured on June 04, 2025.

Daily maximum temperature (left) and daily precipitation totals over Germany, 04.06.2025, source: Wettergefahren-Frühwarnung


East of the cold front, strong diurnal insolation led to sweltering heat south in the Danube Plain. Along the Inn River, temperatures reached up to 30.8 °C at Schäding. The high temperatures were accompanied by high dewpoints reaching up to 19 °C in Southeastern Bavaria. By 12 UTC, strong embedded thunderstorms near the cold front over Eastern France started propagating eastwards along the German-Swiss border. By 14 UTC, a large squall line developed stretching from Bern in the south to Mannheim in the north. The southern part of the squall line showed higher convective activity as it moved across the Swabian Jura into the Danube Plain.

Radar Imagery over Bavaria 04.06.2025 12 UTC - 05.06.2025 00 UTC, source: wetteronline

By 16 UTC, multiple strong cells quickly developed into supercells between Augsburg and Munich. One of the supercells directly affected the northern parts of the metropolitan area of Munich. Reports of heavy downpours, strong winds, and large hail were received from the city. The supercell also affected the football game of the German and Portuguese National teams in Munich. Further west, the squall line impacted the city of Ulm with high winds and heavy downpours.

Approaching squall line near Ulm (left) and hail accumulation near Ulm (right), 04.06.2025, source: Marco Kaschuba


By 18 UTC, three strong supercells moved northeastwards across the Danube Plain. Approaching the Bavarian Forest, the increased orographic lift aided the formation of a large mesoscale convective system (MCS). The transition turned the low-precipitation supercells into a broad complex of heavy convective precipitation with embedded strong convective activity in the southeastern part of the MCS. Along the leading edge of the MCS, a squall-line developed over the central parts of Czechia. The squall line impacted Prague bringing heavy downpours and high winds. By 00 UTC on June 05, 2025, the MCS reached Southwestern Poland. In the second half of the night, the MCS dissipated over Central Poland.

30 min lightning strikes over Central Europe, 04.06.2025 12 UTC - 05.06.2025 02 UTC, source: Blitzortung


High-resolved regional NWP forecasts preceding the event showed the potential for more violent convective activity over Southern Bavaria. The forecasted overlap of high shear and very large CAPE was crucially not realized. For the most potent scenario suggested by the NWP models, the convective activity over the Danube Plain would have been capped until the convection related to the nearing cold front approached. The intermediate scenario was also not realized. In this scenario, convective activity along the Danube Plain would have been initialized by cold pool outflow of the aging convection related to the cold front. In the realized scenario over Southern Germany, the approaching cold front induced mid-tropospheric lift, which led to the formation of a precipitation field west of Munich. This precipitation field deprived the atmosphere of significant CAPE amounts and therefore decreased the maximum potential of the convective activity over Southern Germany. As this precipitation reached more eastwards, strong convective activity started to occur.

Hourly radar-indicated precipitation totals over Germany, 04.06.2025 15 UTC - 23 UTC, source: Wettergefahren-Frühwarnung


This can be taken as one potential hypothesis as to why the observed convective impacts were weaker than initially expected. Nevertheless, the supercells brought heavy downpours with precipitation totals of more than 30 mm, stormy winds with gusts of more than 100 kph, and large hail with diameters of up to 3 cm. Most affected was an area between Munich and Regensburg where multiple supercells formed.

Text: KG
June 05, 2025

© 2004-: IMK, KIT

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