Precipitation life cycle analysis of heavy rainfall events in high-resolution observational data in the southeastern Alpine forelands

In southeastern Austria, the summer season is often characterized by the occurrence of heavy thunderstorms. Typical for these rainfall events is their rapid development, with only a few minutes to hours between the formation of the first clouds and the end of the event. The intense precipitation during these events often results in severe damage, but is difficult to predict. A profound understanding of the life cycle of such events, from formation to dissipation, is therefore crucial to increasing natural hazard resilience and improving forecasting skills.

Here, we investigate the life cycle of 94 heavy rainfall events in high-resolution observational data provided by the WegenerNet 3D Open-Air Laboratory for Climate Change Research (WEGN3D Open-Air Lab) located around Feldbach, Austria. With its 156 ground stations, one X-band radar, two radiometers, and six Global Navigation Satellite System (GNSS) stations, the WEGN3D Open-Air Lab provides high-resolution observations of key atmospheric parameters. By tracking changes in 10 atmospheric parameters connected to heavy precipitation, we gain insights into characteristic features of the different stages of the precipitation life cycle of small-scale rainfall events.

Beginning with the event formation stage (i.e., the 8 h before the event), we find distinct patterns in air temperature, integrated water vapor, liquid water path, and wind speed that are directly linked to the formation of the first storm clouds. During the precipitation stage the highly localized character of these events is clearly visible in the spatial variability of temperature, liquid water path, and cloud cover. In the 16 h after the event (i.e., dissipation stage), we observe the slow return of the atmospheric parameters to pre-event conditions.

Besides being well in-line with the expected physical processes connected to small-scale rainfall extremes, our findings also show that the WEGN3D Open-Air Lab is very skilled in monitoring heavy rainfall events and their characteristics in high spatial and temporal resolution. This illustrates the dataset’s high potential for applications in the improvement and verification of weather and climate models.