Impact-based Warnings Project
Flagship activities

Many National Meteorological and Hydrometeorological Services (NMHSs) are actively pursuing or considering the development of impact-based forecasting and warning (IBFW) services. This represents an explicit attempt to couple traditional estimates of the likelihood of hazardous meteorological or hydrometeorological events with understanding of societal exposure and vulnerability that are fundamental determinants of risk outcomes or impacts. IBFW services involve the estimation of expected consequences and risk outcomes of particular weather events, or sequences and combinations of weather events. This information is communicated to the public and partner organizations involved in the protection of public health and safety, prevention of property and environmental damage, and reduction in the disruption of critical services and attendant social and economic activity.


In support of individual member efforts, the WMO, through its Services Commission experts, produced primary (WMO 2015) and updated (WMO 2021) guidelines on multi-hazard IBFW services. While such efforts are laudable and capture current best practices, existing IBFW services and the underlying assumptions associated with IBFW in general could benefit from further critical examination by social and interdisciplinary scientists. The expert and practitioner members of WMO’s WWRP HIWeather Project are well-suited to take on this challenge by working with and complementing efforts by other national agencies and international groups, including WMO’s Services Commission expert team for impact-based forecasts and warnings and WMO’s initiatives towards strengthening hydrological services. The IBFW project remains an important and outstanding task of the WMO WWRP HIWeather Project, as identified in its implementation plan, particularly through the cross-cutting activity of impact forecasting.


Significant progress has been made by members of the HIWeather Project in understanding the challenges and barriers for IBFW implementation (Kox et al., 2018a, 2018b, 2021; Potter et al., 2021), exploring data needs and data sources for implementation and evaluation (Harrison et al., 2020, 2021, 2022a, 2022b; Spruce et al., 2020, 2021), developing and evaluating hazard and impact models (Hemingway et al., 2019; Robbins & Titley, 2018), and understanding public perceptions of IBFWs (Potter et al., 2018; Taylor et al.,  2019; Weyrich et al., 2018, 2019, 2020a, 2020b). This research provides the building blocks upon which further work towards appropriate and cost-effective development and implementation of IBFW services can commence. Research gaps and questions have been identified from these investigations that require collation and further exploration. 

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