A quantitative precipitation estimate (QPE) provides basic information for the modelling of many kinds of hydro-meteorological processes, e.g., as input to rainfall-runoff models for flash flood forecasting. Weather radar observations are crucial in order to meet the requirements, because of their very high temporal and spatial resolution. Other sources of precipitation data, such as telemetric rain gauges and satellite observations, are also included in the QPE. All of the used data are characterized by different temporal and spatial error structures. Therefore, a combination of the data should be based on quality information quantitatively determined for each input to take advantage of a particular source of precipitation measurement. The presented work on multi-source QPE, being implemented as the RainGRS system, has been carried out in the Polish national meteorological and hydrological service for new nowcasting and hydrological platforms in Poland. For each of the three data sources, different quality algorithms have been designed: (i) rain gauge data is quality controlled and, on this basis, spatial interpolation and estimation of quality field is performed, (ii) radar data are quality controlled by RADVOL-QC software that corrects errors identified in the data and characterizes its final quality, (iii) NWC SAF (Satellite Application Facility on support to Nowcasting and Very Short Range Forecasting) products for both visible and infrared channels are combined and the relevant quality field is determined from empirical relationships that are based on analyses of the product performance. Subsequently, the quality-based QPE is generated with a 1-km spatial resolution every 10 minutes (corresponding to radar data). The basis for the combination is a conditional merging technique that is enhanced by involving detailed quality information that is assigned to individual input data. The validation of the RainGRS estimates was performed taking account of season and kind of precipitation.

Drought is recognized as one of the most complex natural hazards that have a large negative impact on society, economic sectors and the environment. Drought events affect freshwater resources and can become a great threat to urban water supply systems. According to climate change projections with an increase of air temperature and duration of dry periods, cities may experience a serious water shortage in the future that can limit sustainable urban development. Water-related consequences in urban areas can concern various socio-economic sectors as well as urban ecosystems. This paper focuses on drought in urban areas as an event of below-average natural water availability that can result in difficulties in meeting the water needs of socio-economic sectors and ecosystems particularly vulnerable to drought. Drought vulnerable sectors were identified within the local context of the City of Wroclaw area. Long-term analyses of meteorological and hydrological indicators were performed in order to estimate the drought hazard in Wrocław. A combination of water shortage hazard and the vulnerability of water users were the basis to assess local drought risks. Reducing the drought risk requires coherent actions from both city and water managers. The paper presents a set of recommendable measures to avoid potential water shortages and to cope with impacts of drought in the Wroclaw area.

The drought event of 2018–2019 significantly affected most of Central Europe. In this study, the development and intensity of drought in the Lusatian Neisse river catchment were evaluated, based on the indices of SPI, SPEI, and low flow periods related to hydrological drought. Furthermore, multiannual variability in the drought indices, as well as the trends for air temperature and precipitation totals, were examined for 1981–2020. In the catchment, deficit of precipitation was noticed from autumn 2017 to spring 2020, additionally accompanied by a high thermal anomaly. In the summer seasons, heat waves occurred, which intensified evaporation and increased water deficit. The meteorological drought already appeared in spring 2018, developed in the following months, and became more intensive. The frequency of days with discharges >Q_70% exceeded 55%. According to SPI12 and SPEI12, the episode of 2018–2019 can be assessed as the longest period of severe drought in the whole of 1981–2020. The drought caused various consequences in the region. The deterioration of water quality and selected biological indices was one of the effects. In the sector of agriculture, yield reduction in corn and wheat amounted to 33% and 18% in 2018 and 22% and 9% in 2019. In addition, decrease in hydropower generation by more than 30% was noticed.

The automatic procedure of real-time quality control (QC) of telemetric rain gauge measurements (G) has been developed to produce quantitative precipitation estimates mainly for the needs of operational hydrology. The developed QC procedure consists of several tests: gross error detection, a range check, a spatial consistency check, a temporal consistency check, and a radar and satellite conformity check. The output of the procedure applied in real-time is quality index QI(G) that quantitatively characterised quality of each individual measurement. The QC procedure has been implemented into operational work at the Institute of Meteorology and Water Management since 2016. However, some elements of the procedure are still under development and can be improved based on the results and experience collected after about two years of real-time work on network of telemetric rain gauges

Heavy precipitation, and its dependence on atmospheric circulation, is one of the most important weather features in Central Europe. The Polish–Czech Sudetes Mountains and their northern foreland are one of the regions where such precipitation, under certain circulation conditions, often results in floods. The main goal of this paper is to examine multiannual changes in seasonal heavy precipitation between 1961–2020 and to assess their relationship with atmospheric circulation. The data were derived from the Polish and Czech meteorological stations, representing various altitudes and geographical regions. For the purposes of the study, several indices were used, including 1-, 3-, and 5-day maximum precipitation, as well as two indices based on the 90th and 95th percentile thresholds. In the analysis concerning atmospheric circulation, the Lityński classification was considered. The results show that the changes in heavy precipitation usually do not indicate homogeneous directions and are strongly affected by applied indices, seasons, and various geographic factors. Those include the northern/southern slope exposition, which significantly determines heavy precipitation under circulation conditions typical for individual seasons. This particularly concerns heavy precipitation for the north and northeast types, which contribute to higher rates of the considered index, especially in the northern part of the mountains.