The National Weather Service (NWS) issues long-term probabilistic streamflow forecasts through the NWS Advanced Hydrologic Prediction Service (AHPS) web site and is developing methods to issue short-term probabilistic streamflow forecasts. Through customer evaluations of the AHPS web site it became clear that customers do not fully understand the probabilistic graphics and how the information conveyed could be used to make decisions. This is consistent with the quantitative results from the biennial NWS Hydrology Program Customer Satisfaction Surveys, where the probabilistic streamflow forecast graphics received lower marks relative to other graphics. In an effort to better communicate hydrologic forecast uncertainty information, NWS awarded a grant to Aptima, Inc. to improve the display of river and flash flood predictions from a social science perspective. Aptima, Inc. has demonstrated expertise in cognitive science, human factors engineering, modeling and simulation of complex systems, and visual display design. Their approach included knowledge elicitation from a broad range of flood forecast partners, a formulation of a theory of uncertainty as it pertains to flood events, and a design of visualization techniques to maximize the comprehension and utility of flood information specifically for Emergency Managers.

The visualization techniques were designed to maximize the comprehension and utility of river and flash flood forecasts. Specific design features include; the visualization of river forecasts with uncertainty; the visualization of impact of various flooding scenarios; the visualization of uncertainty model inputs; the inclusion of local knowledge into visualization; and improved organization for clear understanding of the relationship between forecasts, impacts and inputs. The proposed visualization techniques were incorporated into the 2008 NWS Hydrology Program Customer Satisfaction Survey to quantitatively assess if these techniques meet the needs of the broader Emergency Management community. The visualization techniques and the results from the Customer Satisfaction Survey will be presented.