Tornado Warnings can be very scary- not only because of the damaging winds they can bring, but also because of the need for sudden and urgent action. Currently, the average time between a Tornado Warning being issued and when a tornado touches down is 13 minutes. Advances in weather technology, however, may be able to increase that lead time by a huge margin. In fact, we soon may be able to give more than one hour of warning before tornadoes hit. But some argue that more than an hour of advance notice is actually too much warning for a tornado. This begs the question: What would you do with that extra time?
But first, let me tell you a little about this extra lead time for tornadoes, and where it's coming from. Our weather forecast models are improving, in part because of the massive upgrade to the GFS model that's currently underway, and also because of the successful launch and implementation of the HRRR, or High Resolution Rapid Refresh model. Other technologies are currently in development, designed to help differentiate between severe thunderstorm cells and "garden variety" thunderstorms. I utilized some of these programs during the Hazardous Weather Testbed's Experimental Warning Program that I participated in last Spring. The most effective programs will be incorporated into the GOES-R satellite, which is scheduled to launch in early 2016. Because of these advances, researchers believe they will be able to give 1-2 hours of advance warning before a tornado touches down by 2020.
So, would 1-2 hours of lead time actually help? A study conducted at the National Weather Center in Norman, OK gave meteorologists some insight. The researchers polled 320 visitors to the Center in 2009; in general, the people in the survey were fairly weather-savvy, but they were not employed in the field. The survey also asked questions designed to determine what length of warning time would be optimal for most people. The study resulted in an optimal warning time of about 34 minutes- way less time than forecasters anticipate that they'll be able to provide.
The survey found that people who do not have a designated tornado shelter (basement, safe room, etc) responded with a desire for more advance warning. This makes sense; some people think their best bet is to evacuate their home and drive to a sturdier shelter. I thought it was interesting that the survey respondents who had previous tornado experience did not prefer longer lead times; the average response from people who have been in a tornado was 29 minutes, in comparison to about 37 minutes from those who had no tornado experience.
The people who responded to the survey had several reasons for rejecting the longer lead times, but most of the reasons boil down to one thing: uncertainty. As of right now, people don't feel that they can 100% trust Tornado Warnings, and to be honest, it's not surprising. The false alarm rate (as of 2009, the date of the survey) was over 75%. This means that more often than not, you are being told to take shelter, even though a tornado will not touch down. But, as I mentioned earlier, improvements in technology will help reduce the false alarm rate, and this should in turn improve confidence, enabling people to take action quickly when a Warning is issued.
Maybe the best way to balance this disconnect is to gradually increase the lead time and let the public recognize that they can trust the advance warning system. As people see that the warnings are more precise, and that false alarms are less common, the technology can be utilized to a greater extent.
It doesn't hurt to mention that, while the false alarm rate is pretty high with Tornado Warnings, the vast majority of tornadoes that actually do occur are covered by a Warning. The tornado "success rate", so to speak, is well over 70%. So, if a Tornado Warning is issued for your area, please take it seriously!
The full article, including detailed survey results, is available here.
