Five challenges to improving NWS tornado warning statistics

Improving tornado probability of detection (POD) and warning lead time and reducing the false alarm ratio (FAR) are ongoing goals of the National Weather Service (NWS). However, progress has slowed over the last decade in improving these statistics. To identify how best to further improve NWS tornado warning statistics, five years (2000-2004) of detailed tornado records and warnings were evaluated. These records were sorted by F-scale, geographically by region and WFO, hour of the day, month of the year, tornado path length, tornado-to-radar distance, county population density, county area, number of tornadoes per day, and tornado order of occurrence.

From these results, five distinct challenges were identified that inhibit further improvements in our tornado warning system. These challenges are: (1) verification; (2) radar coverage gaps; (3) rare events (in geography, season and time); (4) marginally weak events; and (5) transient events (e.g., miso-circulations). Each of these challenges will be discussed in detail with some solutions offered on how to overcome these barriers to improving our tornado warning operations.