Tornadoes without NWS warning
Results show that the tornadoes most likely to strike when the public is least likely to be aware are also those tornadoes with the greatest chance of not being warned. Singular tornado events (one tornado report per day within a WFO County Warning Area) and the first tornado report of the day were the most difficult scenarios on which to warn, with over half of all single tornado events not warned. Weak, isolated, and nocturnal tornadoes had a much higher ratio of not being warned. Geographic areas that experience a significant proportion of weak, isolated, and/or nocturnal tornadoes, such as Florida and the western U.S., had a much higher ratio of missed warnings. In general, the stronger the tornado, as estimated from its F-scale and/or track length, the greater chance it was warned. However, many weak tornadoes were not warned, and the overall ratio of missed tornado warnings to reported tornadoes actually increased over more densely populated regions, likely due to more complete post-event verification. The tornado distance from radar had a significant impact on tornado warning statistics. Due to a small sample size, storm classification results were inconclusive, but suggest that linear events may lead to more missed warnings.