Intense convective storms cause many deaths around the world each year from flash floods, landslides, lightning, tornadoes and hail. These are also some of the most difficult to forecast weather hazards and are generally not predictable in a deterministic sense by Numerical Weather Prediction models. In the UK the incidence of such storms has increased significantly in recent years, as a result of climate change, and is projected to increase further with increasing summer temperatures and corresponding increases in absolute humidity. The current UK weather warning service is focused on providing early warnings of six or more hours lead time to enable people to plan ahead for safety. However, the small spatial and temporal scales of convective storms mean that only a very general probabilistic indication can be given of timing and location in these warnings. As a result, most recipients do not prepare for the possibility of severe impacts, even when the accompanying message indicates that they are possible. One option being considered for enhancing the current warning service is to developed a complementary very short range warning focused on storms that present a risk to life. This implies a particular set of responses from warning recipients which make specific demands on the information communicated and the means of communication. On the other hand, current forecasting capabilities for these storms are limited and there are known constraints to forecast improvement. This presentation will demonstrate how a value chain approach has helped to identify the critical components of such a warning system, mapping them on to existing and projected capabilities. Results of a preliminary feasibility study will be shown.

How to cite: Golding, B.: Application of the warning value chain in designing a new warning capability for the UK, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-116, https://doi.org/10.5194/ems2023-116, 2023.

Several changes have been made in Norway over the last five years. The warnings are now issued in both Norwegian and English, and include color/warning level, advises, expected impacts, illustrations and probability information. The CAP format is used and warning dissemination is also made available through a broader range of media and specifically in social media channels. The warnings also include wording regarding impacts and wanted behavior.

MET Norway is strongly involved in risk assessments regarding probabilities of weather exceeding given thresholds i.e. traditional forecasting, and now routinely participates in video conferences with important contingency actors on incident handling. Verification reports are also written regularly after orange and red warnings, and a weekly report of the issued warnings and their impacts are made.

Gradually more phenomena have been included in the warning service by expert teams (meteorologists specialized on a certain phenomenon), based on feedback on user needs as well as the effects of a changing Norwegian climate. Flash-floods are an example of a phenomena that has occurred more often in recent years with a lot of damage and impact on transportation and other sectors.

Even though the thresholds for the warnings are still meteorologically based, they are based on return-values and/or discussed with large user-segments as the road-authorities, seen in the perspective of expected impacts. Norway is a country with a lot of mountain roads so to warn the different drivers about possible problems or a closed road is of large socio-economic importance.

A lot of the impacts and advice used are based on dialogue with relevant user groups. In the presentation the weather warning process and service in Norway will be shown and a glimpse into our plans to even improve it more.

How to cite: Agersten, S. and Sivle, A.: The way towards impact based warnings in Norway, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-521, https://doi.org/10.5194/ems2023-521, 2023.

The warning value chain is a concept whereby the process of producing a warning is represented by a chain of sources of expertise (components), connected by bridges that convey bidirectional information exchanges. Uncertainties exist at all stages of the warning value chain. For example, uncertainties exist in the current (observational) state of the atmosphere used to initialise the numerical weather prediction models. This in turn contributes towards weather forecast uncertainties (e.g., ensemble-generated forecast probabilities and run-to-run variability). Weather forecast uncertainties then feed into the hazard and impact forecasts where they can be amplified – such as through uncertainties in defining hazard footprints or impact assessments. Often it comes down to operational meteorologists to examine the varying levels of forecast uncertainty across several value chain components and assess the real likelihood of high impact weather and its potential impacts. This presentation will focus on the challenges of forecast uncertainty within the value chain, using the forecasts and warnings associated with Storm Eunice which affected southern parts of the UK in February 2022 as an example. The Met Office Weather Impacts team recently used the warning value chain questionnaire produced by the WMO’s High Impact Weather (HIWeather) Warning Value Chain Flagship Project, to carry out a detailed warning value chain assessment for this event, where evidence was considered from across the value chain. Results showed that all components of the value chain performed well overall, and it was clearly a highly successful set of warnings as shown by the large reach and public/emergency response. However, several recommendations were still made and challenges resulting from forecast uncertainty were evident across many value chain components. A focus of this presentation will be on how operational meteorologists interpreted the changing forecast signal and how this affected warning issuance and communication.

How to cite: Neal, R., Titley, H., Golding, B., Jones, C., Kolusu, S., Mooney, J., Robbins, J., and Wyatt, F.: Challenges of forecast uncertainty within the warning value chain – a UK example from Storm Eunice, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-42, https://doi.org/10.5194/ems2023-42, 2023.

The European Flood disaster caused widespread devastation across national borders between the 14-15^th  July 2021 with an estimated total damage of EUR 32 billion. The disaster brought human suffering to the communities hardest hit with hundreds of reported casualties in western Germany and eastern Belgium. Serious doubts about the efficacy of Early Warning Systems (EWSs) were raised by scientists, politicians and flood victims. The response to the hazard was largely delayed and deficient in terms of warning dissemination to vulnerable groups. Institutionally, the disaster was often deemed unpredictable and extraordinary by decision-makers. However, knowledge risk on the predictability of the hazard has since demonstrated that, precursor signs of a major flood event were detected by the EFAS almost a week ahead of the event. Signs of a potential extreme hydrometeorological event were identified by July 10^th by ECMWF’s Extreme forecast Index (EFI). The DWD accurately forecasted the potential for an extraordinary precipitation event at least 48 hours in advance in Germany and in neighbouring affected countries. Despite initial uncertainties related to precise prediction of total rainfall amounts, this was a well forecasted hazard and not unexpected. In the Aftermath of the disaster,  Germany and in Belgium were faced with investigations against neglect of officials during the floods and manslaughter accusations over flood deaths. Meanwhile, Luxembourg, a small country nestled between the most affected regions of Germany and Belgium respectively went largely unnoticed and questions related to the flood response mostly unanswered. The paper will focus on Luxembourg, addressing knowledge gaps relating to the existing disaster management mechanisms and policies in place during the event. Preliminary research on the existing disaster management mechanisms and policies in place will examine Luxembourg’s conceptualisation of what EWSs are and how they performed during the flood event in 2021. Aspects of people-centred EWSs (Risk Knowledge, Monitoring and Warning, Warning Dissemination and Communication, Response Capability) will be considered. A systems thinking approach will enable for a detailed timeline of events related to the functioning of EWSs. The main objective is the exploration of the complex links and dynamics involved in the flow of information during critical phases of disaster management. The case study questionnaire made available by the WMO WWRP Value Chain Framework Project will act as a guide to extract and conceptualise information flows. Expected outcomes are the identification of potential shortcomings and strengths of the system. The absence of a universal definition for EWSs and their place within disaster management frameworks highlights the need for future research of disaster risk in the context of extreme events. Root causes leading to gridlocks in currently operational EWSs are non-linear and call for integrated disaster risk research approach.

How to cite: Da Costa, J., Cloke, H., Neumann, J., and Robinson, S.: Unprecedented but not unexpected: A case study of the European Flood disaster 2021 in Luxembourg using a value chain approach., EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-435, https://doi.org/10.5194/ems2023-435, 2023.