Investigating How NWS Meteorologists, Emergency Managers, and the Public Interpret Conditional Intensity Forecasts for Severe Weather

Abstract Continued research of severe convective storms has enhanced the forecast capabilities of products like the Storm Prediction Center’s (SPC) convective outlook. Since 2003, the outlook has presented information about the likelihood of convective hazards within 25 mi of a point, as well as a “hatched” area where a 10% or greater chance of hail larger than 2 in. in diameter, thunderstorm winds greater than 75 mph, or tornadoes of EF2 strength or greater exists. The SPC has begun testing more detailed forecasts of potential storm intensity and is now seeking to design a product that can effectively communicate this new information. To aid in the development of effective intensity forecast information for the SPC outlook, this study conducted surveys and focus groups with members of the public, National Weather Service meteorologists, and emergency managers, recording their feedback on how they thought this information would change their perceived concern and intended behavior on severe weather event days. We also investigated how different presentations of intensity information impact risk perceptions and understanding of the weather event. The inclusion of intensity information increased the perceived concern of members of the public and emergency managers. Changes to the way that intensity forecast visuals were presented also impacted perceived concern and likelihood of response, suggesting that caution must be taken in deciding what the operational version of the convective outlook should look like. Significance Statement As severe weather science advances, the Storm Prediction Center (SPC) has begun to develop the capacity to forecast where significant tornadoes (EF2 or greater), winds (75 mph or greater), and hail (2 in. in diameter or greater) will occur. However, this new forecast information needs to be packaged into a visual format that can effectively communicate severe weather intensity to users ranging from emergency managers to members of the public. Through a series of surveys and focus groups, this study investigates how different user groups interpret several conditional intensity forecast prototypes. Findings suggest that simplified, separated forecasts graphics are preferred to graphics that layer information in one image, and that, although more development is needed, users are able to incorporate conditional intensity information into their decisions around protecting themselves from severe thunderstorms.