Convective and stratiform heavy and extreme precipitation in a changing climate: Insights from Central Europe

Precipitation in Central Europe occurs in diverse forms, with significant hydrological and societal impacts depending on its character and intensity. Two dominant types—convective and stratiform precipitation—differ not only in their spatial and temporal development but also in their association with atmospheric circulation patterns. Convective precipitation is often linked to rapid, localized storms capable of causing flash floods, whereas stratiform precipitation is typically associated with widespread, prolonged rainfall events that may lead to regional flooding.

We analyze heavy and extreme precipitation in both the recent climate and under two future climate scenarios: SSP5-8.5 and SSP2-4.5. For the recent climate, we use observational time series from 19 meteorological stations across the Czech Republic, covering the period 1982–2021. Precipitation events are classified as convective or stratiform using an automated algorithm based on SYNOP weather reports. To assess projected changes throughout the 21st century, we utilize the ALADIN-CLIMATE/CZ regional climate model, operated by the Czech Hydrometeorological Institute, which provides simulations at a high horizontal resolution of 2.3 km. Heavy precipitation events are defined as those exceeding the 90th percentile threshold. To further quantify extremes, we estimate 50-year and 100-year return values for convective and stratiform precipitation using a Generalized Extreme Value (GEV) distribution fitted to annual maxima.

To investigate the driving mechanisms behind heavy precipitation events, we will assign circulation types using the Jenkinson & Collins (1977) classification scheme. This approach is based on three key indices: direction, flow strength, and vorticity. This method distinguishes 27 distinct circulation types. Our results indicate a pronounced seasonal and spatial variability in the relationship between circulation patterns and precipitation types. Heavy stratiform precipitation events are most associated with cyclonic circulation and directional flows from the west and north. During summer, however, heavy convective precipitation also frequently occurs under anticyclonic and unclassified conditions, highlighting the role of localized atmospheric instability and mesoscale processes in triggering intense rainfall during warmer months. An important question is how the relationship between heavy precipitation and atmospheric circulation will evolve under future climate conditions.