Weather-Ready Nations

Impact-based forecasting in decision support systems


Our impact-based forecasting initiative is an effort to develop decision support systems at national meteorological and hydrometeorological services that will provide information about the impact of a hydrometeorological hazard, or multi-hazards, to an individual or community at risk. In the case of both weather forecasts and warnings, the focus is on what the weather will be will evolve to what the weather will do and how it will impact a community.


  • Improve products and services for decision-making
  • Deliver potential impact of forecast weather
  • Provide training on implementing impact-based forecasting techniques at National Meteorological and Hydrological Services


  • Improved planning for different scenarios based on different thresholds, impacts or combinations of impacts occurring
  • Better contingency planning (best, reasonable worst-case and most likely outcomes)
  • Information about level of confidence in the forecast that would convey additional information for better decision-making (a more informed risk assessment)
  • A comprehensive and coordinated process to address disaster response and preparedness
  • Common situational awareness


For impact forecast and warning services, exposure is explicitly considered along with the hazard and vulnerability. These types of forecasts and warnings are designed to provide detailed information precisely on who or what is exposed.

In order to provide these types of warnings, NMHSs (or the responsible government agency) must have available detailed vulnerability and exposure information relevant to the hazard and individual entities for whom (or which) the forecasts are provided. Impact forecast and warning services can only be provided in instances where an NMHS has developed strong partnerships with other relevant agencies or with user communities.

Impact forecasts and warnings relay a message of greater relevance to enable those at risk to take appropriate actions in order to mitigate the overall adverse effects of hydrometeorological hazards.

Example Implementation

Barbados has been identified in need of capacity development for implementation of Storm Surge and Inundation, Flash Flood, Flood and Landslide early warning systems and impact-based forecasts and warnings. Barbados is a member of the Caribbean Meteorology Organization (CMO) Member States as well as CDEMA Participating States. Barbados has been working with the Caribbean Institute for Meteorology and Hydrology (CIMH), the Caribbean Disaster and Emergency Management Agency (CDEMA), and the Eastern Caribbean Disaster Program Group/Disaster Management (ECDPG/DM) to risk inform planning of activities related to severe weather events in Eastern Caribbean States. This project is supporting the implementation of an Impacts-Based Forecast System (IBFS) and the expansion of standard operating procedures (SOPs) to include IBFS in Barbados and eventually other CMO countries.

A formalized IBFS has been established in Barbados. The main stakeholders in the IBFS implementation has been the Barbados Meteorological Service (BMS), Barbados Department of Emergency Management, (DEM), and CIMH. BMS, DEM, and CIMH have taken the lead in developing standardized hazard matrices for the various hazards that require early warning and impact-based forecasting, including high winds, severe convection, and heavy rainfall events. The list of hazards identified by the stakeholders in Barbados are provided in the table in the Appendix. Secondary stakeholders have been included in developing the impact and risk and response matrices. The agencies include CDEMA, Coastal Zone Unit (CZU), airport operations, first responders, harbor operations, and other groups that depend on DEM for guidance during high-impact hazardous events.

The project has been following the six-phase IBFS implementation guidance that has the following components:

  • Phase 1: Collect data and develop hazard, risk and response matrices
  • Phase 2: Expand stakeholder participation
  • Phase 3: Develop forecaster and disaster management interface
  • Phase 4: Develop standard operating procedures
  • Phase 5: Impact-based forecasting demonstration
  • Phase 6: Public awareness and outreach