EFFECTIVELY COMMUNICATING RISK AND UNCERTAINTY TO THE PUBLIC Assessing the National Weather Service's Flood Forecast and Warning Tools

Given the constant bombardment of weather information in different formats and time frames with different levels of certainty, how does an important message make an impact? For weather and river forecast offices, this is a pressing question given a likely future of increasing high-impact storm events. These offices need to quickly and effectively motivate public response to impending events such as flooding. Currently, communication of flood potential is accomplished through a suite of forecast and warning products, including river hydro graphs, precipitation forecasts, and flood watches and warnings. Despite advances in forecast accuracy and lead time, people fail to respond to warnings and often suffer substantial damages and loss of property. To understand how the public uses and interprets National Weather Service (NWS) flood products, an extreme storm scenario was presented using NWS forecast products in a series of focus groups in the Delaware River basin (Pennsylvania-New Jersey). Findings from the sessions informed revisions of the products to which participants reported increased understanding and motivation to take action. Participants demonstrated a strong preference for river-level information presented through the NWS hydro graph among all the NWS products shown depicting an approaching hurricane. Simplified graphics, explanations in general terms, intuitive colors, and geographic specificity are key recommendations to improve comprehension of risk and uncertainty. The National Oceanic and Atmospheric Administration (NOAA) and NWS are taking steps to operationalize some of these suggestions. This study's methods and results are applicable to other areas and hazard types.