Severe thunderstorms with large hail across <scp>Germany</scp> in <scp>June</scp> 2019

Wilhelm, Jannik; Mohr, Susanna; Punge, Heinz Jürgen; Mühr, Bernhard; Schmidberger, Manuel; Daniell, James; Bedka, Kristopher M.; Kunz, Michael

doi:10.1002/wea.3886

Cited by 24 publications

(15 citation statements)

References 11 publications

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“…Numerous studies focus on single severe storms in or near complex terrain in Europe [35][36][37][38][39][40][41][42][43] , in the USA [44][45][46] and South America 47,48 . A broader stance is taken in several studies [49][50][51] , where clusters of severe thunderstorms causing large hail and flash floods in central Europe are analysed. Studies in Italy investigate the conditions leading to tornadoes throughout the country 52 , as well as the distribution of lightning in the Northeastern region ranging from the Adriatic coast to the Julian Alps 53 .…”

Section: Severe Thunderstormsmentioning

confidence: 99%

Hailstorms and rainstorms versus supercells—a regional analysis of convective storm types in the Alpine region

et al. 2023

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The behaviour of severe thunderstorms, particularly supercells, in complex terrain is still poorly understood. Utilising 6 years of radar-, lightning- and radiosounding-based thunderstorm data in the domain of the Swiss radar network, we study different thunderstorm types in separate topographical regions. We classify the storms as ordinary thunderstorms, intense and severe rainstorms, hail and severe hailstorms and supercellular storms. After identifying the overlaps between the storm categories of rainstorms, hailstorms and supercells, the life cycles of several intensity metrics are investigated. This analysis allows the identification of predictors for intensification within severe storm life cycles. One of the most important predictors is the detection of a mesocyclone in a supercell before the onset or intensification of hail. We then divide the radar domain into sub-regions ranging from the Northwestern Po Valley, the Southern Prealps, main Alpine ridge, Northern Prealps, Swiss Plateau and Jura. This regional split separates storms in different terrain complexities. An investigation of the intensity distribution of storms in each region shows a clear intensity decrease over the main Alpine ridge, intermediate values over the moderately complex Prealpine regions and peaks for the flat Po Valley and Swiss Plateau. In contrast, the highest frequency of storms is found in the Prealpine regions on each side, with a lower frequency in the flat areas and a minimum in convective activity over the main Alpine ridge.

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Section: Severe Thunderstormsmentioning

confidence: 99%

Hailstorms and rainstorms versus supercells—a regional analysis of convective storm types in the Alpine region

et al. 2023

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“…The weakly forced case of 9 June 2018 belongs to a long-lasting episode with severe thunderstorms described in more detail by Mohr et al (2020). Wilhelm et al (2021) gives a detailed description of the synoptic controls of the 3-day storm series in June 2019 to which our last case (11 June) belongs to. To evaluate the synoptic-scale forcing quantitatively, we calculated the convective adjustment time scale following the approach of Keil et al (2014).…”

Section: Case Studiesmentioning

confidence: 99%

Importance of aerosols and shape of the cloud droplet size distribution for convective clouds and precipitation

Barthlott

Zarboo

Matsunobu

et al. 2021

Preprint

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Abstract. The predictability of deep moist convection is subject to large uncertainties resulting from inaccurate initial and boundary data, the incomplete description of physical processes, or microphysical uncertainties. In this study, we investigate the response of convective clouds and precipitation over central Europe to varying cloud condensation nuclei (CCN) concentrations and different shape parameters of the cloud droplet size distribution (CDSD), both of which are not well constrained by observations. We systematically evaluate the relative impact of these uncertainties in realistic convection-resolving simulations for multiple cases with different synoptic controls using the new icosahedral nonhydrostatic ICON model. The results show a large systematic increase in total cloud water content with increasing CCN concentrations and narrower CDSDs together with a reduction in the total rain water content. This is related to a suppressed warm-rain formation due to a less efficient collision-coalescence process. It is shown that the evaporation at lower levels is responsible for diminishing these impacts on surface precipitation, which lies between +13 % to −16 % compared to a reference run with continental aerosol assumption. In general, the precipitation response was larger for weakly-forced cases. We also find that the overall timing of convection is not sensitive to the microphysical uncertainties applied, indicating that different rain intensities are responsible for changing precipitation totals at the ground. Furthermore, weaker rain intensities in the developing phase of convective clouds can allow for a higher convective instability at later times, which can lead to a turning point with larger rain intensities later on. The existence of such a turning point and its location in time can have a major impact on precipitation totals. In general, we find that an increase in the shape parameter can produce almost as large a variation in precipitation as a CCN increase from maritime to polluted conditions. Narrowing of the CDSD not only decreases the absolute values of autoconversion and accretion, but also decreases the relative role of the warm-rain formation in general, independent of the prevailing weather regime. We further find that increasing CCN concentrations reduces the effective radius of cloud droplets stronger than larger shape parameters. The cloud optical depth, however, reveals a similar large increase with larger shape parameters as changing the aerosol load from maritime to polluted. By the frequency of updrafts as a function of height, we show a negative aerosol effect on updraft strength, indicating that the larger water load above the freezing level in polluted conditions does not lead to an invigoration of deep convection. These findings demonstrate that both, CCN assumptions and the CDSD shape parameter, are important for quantitative precipitation forecasting and should be carefully chosen if double-moment schemes are used for modeling aerosol-cloud interactions.

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“…During these events, hail with a diameter of up to 6 cm was observed and heavy rain with a daily amount of 100 mm was measured. Wilhelm et al (2020) describe this series of convective storms in detail. In our study, we define the events that precede the measurements taken on the evening of 10 June 2019 as Case 1 and the ones preceding the measurements taken in the evening of 11 June 2019 as Case 2.…”

Section: Meteorological Situation At the Time Of The Case Studymentioning

confidence: 99%

A case study on the impact of severe convective storms on the water vapor mixing ratio in the lower mid-latitude stratosphere observed in 2019 over Europe

Khordakova¹,

Rolf²,

Grooß³

et al. 2021

Preprint

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Abstract. Extreme convective events in the troposphere not only have immediate impacts on the surface, they can also influence the dynamics and composition of the lower stratosphere (LS). One major impact is the moistening of the LS by overshooting convection. This effect plays a crucial role in climate feedback as small changes of water vapor in the upper troposphere and lower stratosphere (UTLS) have a large impact on the radiation budget of the atmosphere. In this case study, we investigate water vapor injections into the LS by two consecutive convective events in the European mid-latitudes within the framework of the MOSES (Modular Observation Solutions for Earth Systems) measurement campaign during the early summer of 2019. Using balloon-borne instruments, rare measurements of the convective water vapor injection into the stratosphere were performed. The magnitude of the water vapor reached up to 12.1 ppmv with an estimated background value of 5 ppmv. Hence it is in the same order of magnitude as earlier reports of water vapor injection by convective overshooting above North America. However the overshooting took place in the extra-tropical stratosphere and has an impact on long-term water vapor mixing ratios in the stratosphere compared to the Monsoon-influenced region in North America. At the altitude of the measured injection, a sharp drop in a local ozone enhancement peak makes the observed composition of air very unique with high ozone up to 696 ppbv and high water vapor up to 12.1 ppmv. While ERA-Interim data does not show any signal of the convective overshoot, the measured values in the LS are underestimated by MLS satellite data and overestimated by ERA5 reanalysis data. Backward trajectories of the measured injected air masses reveal that the moistening of the LS took place several hours before the balloon launch. This is in good agreement with reanalyses and satellite data showing a strong change in the structure of isotherms, and a sudden and short-lived increase in potential vorticity at the altitude of the trajectory, as well as low cloud top brightness temperatures during the overshooting event.

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Severe thunderstorms with large hail across Germany in June 2019

Cited by 24 publications

References 11 publications

Hailstorms and rainstorms versus supercells—a regional analysis of convective storm types in the Alpine region

Hailstorms and rainstorms versus supercells—a regional analysis of convective storm types in the Alpine region

Importance of aerosols and shape of the cloud droplet size distribution for convective clouds and precipitation

A case study on the impact of severe convective storms on the water vapor mixing ratio in the lower mid-latitude stratosphere observed in 2019 over Europe

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