Emergency managers play a critical role in distributing NOAA National Weather Service warnings to people using a variety of methods, such as activating sirens, notifying schools, hospitals and other critical services, activating an emergency alert system, cable television interrupt, or a reverse emergency call-out system. Emergency managers play an integral role in the testing, evaluation, and feedback during the development of probabilistic hazard information within the NOAA Hazardous Weather Testbed. They provide feedback on their interpretation of experimental probabilistic forecasts generated in the HWT from the PHI Experiment and the Experimental Forecast Program. This feedback is used in conjunction with feedback from forecasters and broadcast meteorologists to refine how the uncertainty information is generated and disseminated. In addition, NSSL collaborators conduct ethnographic research with emergency managers during live events. This helps researchers understand the complex decision-making processes of emergency managers during severe weather outside controlled testbed environments.