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A regional reanalysis covering the years 1989-2010 has been produced with the HIgh Resolution Limited-Area Model (HIRLAM) forecast model and data assimilation system. Surface and upper-air variables were analysed at 0000, 0600, 1200 and 1800 UTC on a three-dimensional grid-mesh with 22 km spacing covering Europe using conventional insitu observations. Information from the global reanalysis ERA-Interim has been used as a large-scale constraint in the data assimilation and as lateral boundaries in the forecast model integrations. Comparison to the global forcing reanalysis shows good agreement in the large-scale structures, as expected given the forcing from the boundaries and in the analysis. Comparison to the observed climatological distribution and a skill score evaluation showed that the HIRLAM reanalysis is better than ERA-Interim at describing extreme values of 2 m temperature and 24 h accumulated precipitation. However, no added value in the HIRLAM reanalysis could be quantified for the wind speed at 10 m over land. The first production run covered the years 1989-2010 and the statistics presented in this paper are based on that dataset. This reanalysis has also been used as input to a two-dimensional surface analysis using the MESoscale ANalysis (MESAN) system which is presented in Part 2. Since then both the two- and three dimensional reanalyses have been extended to cover the years 1979-2014. [ABSTRACT FROM AUTHOR]

Following trends in operational weather forecasting, where ensemble prediction systems (EPS) are now increasingly the norm, flood forecasters are beginning to experiment with using similar ensemble methods. Most of the effort to date has focused on the substantial technical challenges of developing coupled rainfall-runoff systems to represent the full cascade of uncertainties involved in predicting future flooding. As a consequence much less attention has been given to the communication and eventual use of EPS flood forecasts. Drawing on interviews and other research with operational flood forecasters from across Europe, this paper highlights a number of challenges to communicating and using ensemble flood forecasts operationally. It is shown that operational flood forecasters understand the skill, operational limitations, and informational value of EPS products in a variety of different and sometimes contradictory ways. Despite the efforts of forecasting agencies to design effective ways to communicate EPS forecasts to non-experts, operational flood forecasters were often skeptical about the ability of forecast recipients to understand or use them appropriately. It is argued that better training and closer contacts between operational flood forecasters and EPS system designers can help ensure the uncertainty represented by EPS forecasts is represented in ways that are most appropriate and meaningful for their intended consumers, but some fundamental political and institutional challenges to using ensembles, such as differing attitudes to false alarms and to responsibility for management of blame in the event of poor or mistaken forecasts are also highlighted. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The extreme dependency score EDS has been recently proposed as a nonvanishing measure of skill to verify predictions of rare events. An idealized example is employed to investigate the properties of the EDS when the probability of the event happening is small, as is the case for rare events. The paper warns about the nondependency of EDS on the false alarms and the correct rejections when the sample size is fixed, which encourages hedging. Thus, the EDS should not be the sole score used to assess a models performance on forecasting rare events. The dependency of the EDS on the event probability base rate is also analysed. It is shown that the EDS can be written as a function of the base rate and the hit rate, and that only in a very particular condition the score is independent of the event probability. Therefore, when comparing forecasts skills in terms of the EDS, special attention has to be paid to separate the variations in skill from the variations of the probability that the event happens over time.The score is used to assess the performance of the ECMWF deterministic precipitation forecast over Europe for different forecast ranges and precipitation thresholds. Verification of precipitation forecasts in terms of EDS, combined with an assessment of the false alarm rate, shows a clear improvement of the ECMWF deterministic forecast for precipitation of rare events i.e. large rainfall amounts. Copyright © 2009 Royal Meteorological Society [ABSTRACT FROM AUTHOR]