Impacts of Time of Day and Year on Severe Warning Performance over the United States Great Plains

Severe weather warnings are used to warn the public about imminent threats to life and property. Over the last few years, the national false alarm ratio (FAR) has been around 0.49 and the probability of detection has been 0.78. While there has been research into how tornado warning verification has evolved by time of year and time of day, a similar study has not been done for severe thunderstorm warnings which constitute a large majority of warning issued across the United States. Our study will identify how warning performance varies by hour of the day, month of the year, season, and distance of the warning or event from the nearest radar for seven National Weather Service forecast areas in the Great Plains of the United States. Our analysis will examine the role that non-meteorological factors may play in warning performance due to fewer spotters available at night, decreased sampling of the storm as distance from the radar increases, and whether wind or hail events are more difficult to detect and whether that changes by time of day. Identifying periods of increased or decreased performance can help NWS meteorologists identify both training needs and further research that can act to improve detection and decrease false alarms for severe weather warnings.