The Impact of NWS Weather Forecast Office Culture on Tornado Warning Performance

Tornado warnings are a mission critical function of the National Weather Service (NWS). Metrics on NWS performance in this area have been calculated for decades and used to monitor the impacts of new tools, technologies, and science on improving overall performance. Such metrics include the Probability of Detection, False Alarm Rate (FAR), Lead Time, and Critical Success Index (CSI).

In this study, we look at the impact of local NWS Weather Forecast Office (WFO) culture on tornado warning performance. WFO culture is quantified through a Culture Index which was derived from a statistical analysis of data from an employee satisfaction survey administered in 2002. Employees at WFOs with a relatively high value on the Culture Index tend to feel better about their overall work environment and vice versa.

The results of the study show that, over a nearly 20-year period, the WFOs scoring in the top one third of the Culture Index have consistently outperformed other WFOs in tornado warning CSI. This skill is primarily due to these same WFOs achieving a consistently low FAR over the same period.

In examining the 2011 Joplin, Missouri and Tuscaloosa, Alabama large-fatality tornadic events, Simmons and Sutter (2011) found evidence of a false alarm effect, as a higher recent, local false alarm ratio (FAR) significantly increases fatalities and injuries. Similarly, the NWS Service Assessment on the Joplin event stated “While there are no guarantees that simply decreasing false alarms will significantly impact warning response behavior, the results of the Joplin residents interviews appear to indicate a relationship between perceived false alarms, degree of warning credibility, and complacency in warning response.”

Our results are consistent with these findings. The WFOs in the top third of the Culture Index also experience significantly fewer tornado-related fatalities. This talk will also include a discussion of a causal mechanism for how WFO culture affects tornado warning performance.