Increasing tornadoes or better information gathering?

John Kerry’s comment about the recent tornadoes in the southeastern USA being caused by “global warming” has caused more than a few dustups on the Internet blogs in the last couple of days.

So, from the perspective of a former TV meteorologist, I thought I’d share some of my thoughts about modern tornado statistics.


Graph from NWS/NOAA. Smaller (F1) tornadoes seem to be on the increase, but not larger ones.

I see it as simply increased reporting bias. No I’m not talking about talking heads in news stories, but rather, our ability to detect and report tornadoes has increased dramatically in the last 50 years.

There are three main reasons:

1) Our 155 strong WSR-88D NEXRAD Doppler Radar Network. This nationwide tool sees tornadoes with more regularity than the old WSR74 and WSR57 C band analog radars which used to be the mainstay of the NWS radar network. Often tornadoes that would have gone undetected and unseen before (such as in unpopulated areas) are reported with accuracy by Doppler radar. You can even download software now for your PC and get in on the action yourself. See my StormPredator program, for example.

2) Increased population density. There are more people around in places that used to be uninhabited resulting in more tornado reports where before they went unseen. It is sort of like a twist on that old saying: “If a tree falls in the forest and there’s nobody to hear it, does it make a sound?”

3) More reporting coverage. TV news and storm chasers make getting tornadoes on live TV almost as regular as watching LA car chases. Helicopters with video feeds, live vans, and just regular folks with a K-Mart video camera in the right place at the right time increase the frequency with which we see severe weather events on TV, resulting in the “feeling” that such events are on the increase.

A person from the year 1900 watching The Weather Channel today would probably think we were living in the end times.

Oddly, even with such a major increases in our reporting and news gathering ability, plus inexpensive digital cameras and camcorders in the hands of people worldwide, we have not had an increase in good photo or video evidence of UFO’s, Bigfoot, or Loch Ness.

But that’s a blog argument for another day.

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Stu Miller
February 8, 2008 9:44 pm

Could you annotate the graph to indicate when the upgraded radars were installed, or at least give a range of dates for installation of the WSR 57, 74, and 88 radars? How do those dates correlate with the number of small storms being detected?
Stu Miller

David Walton
February 8, 2008 10:41 pm

Re: “…we have not had an increase in good photo or video evidence of UFO’s, Bigfoot, or Loch Ness.”
Yeah, but the nonsense on radio has proliferated nicely thanks to the kook-sphere created by Art Bell and carried on by George Noory. Sheesh, those two really make me cringe.

February 9, 2008 6:22 am

The number in the radar name references the year it was developed so the 88 was supposed to start deploying about 1988, although it took some time to get them out there (it was originally supposed to be 1986 as I remember). I assume the other two are circa 1957 and 1974. The 57 and 74’s could only identify by “hook echo” since they didn’t have a doppler capability to measure winds. Never did find out how well the 88’s TVS (Tornado Vortex Signature) algorithm works.
Another reason for more reports may be better ground analysis of the damage where they’re identifying tornadoes which may have been just thought of as high wind gusts before.
REPLY: Barry you know your radars. Before the WSR-57 was the WSR-3 which I had the opportunity to work on (actually rebuild). It was part surplus aviation radar converted to ground use. Tubes, cotton insulated wires, 1N21 diodes and an early klystron tube. It had more knobs and internal rheostats than Hansens model E

An Inquirer
February 9, 2008 6:32 am

One historical note and then a philosophical note. When I was a kid in the 50s and 60s, our farm family would see tornadoes most summers. Sometimes, we would head to the basement. Other times, we would watch them across the valley — we had a great view. In the last twenty years, I do not remember any tornadoes. (Yes, purely ancedotal, but it never occurred to us to report the tornadoes forty or fifty years ago.) Philosophically, this media and blogging buzz about tornado numbers is another indication of the woeful job our education system is doing in teaching our children/teenagers/adults about data and analysis. I tell my students that emotional competence is a higher order thinking skill, but if you do not understand data and if you cannot analyze cause/effect, then your emotional competence is suspect and maybe even dangerous. Unintended consequences are likely to abound.

Gary Gulrud
February 9, 2008 7:48 am

Interesting ‘end times’ Wiki Rev., its intriguing to see what some of the authors find worth commenting on but there is some good info in there. Funny they don’t follow up on the ‘Abomination causing desolation’ a bit further with the links to the Moabite worship of Chemosh and the locale of reappearance as the vale of Hinnom.

February 9, 2008 8:05 am

The answer is in red. While the total number of reported tornadoes has steadily increased the number of F2’s and above has actually decreased from the 1960s and 70s. If you correlate the number of annual F2+’s with temperature I suspect you will find a nice fit …. inversely that is.

February 9, 2008 8:24 am

I actually supported the development of the WSR-88D from about 1983 to 1987 on the software side. There was a competition between Unisys and Raytheon for the contract. Interesting job since each company had different approaches and strengths, the but extremely frustrating at times. Trying to get them to do unit testing or document what they were doing was a nightmare. They wound up using Fortran because the contract required an ANSII standard language and that was the only one available at the time. Also got to work with some of the researchers from Norman, OK who developed the algorithms for the weather doppler radars.

David Walton
February 9, 2008 12:35 pm

You guys talking radar got my attention. I know next to nothing about radar (except some of the basics). My father, who was a gifted mathematician and went on to become a PhD chemist, was a radar man for the Army in WW2.

October 5, 2008 9:26 am

[…] NWS/NOAA. Smaller (F1) tornadoes seem to be on the increase, but not larger ones (F2-F5). This is likely due to increased reporting from Doppler Radar, storm chasers, and news gathering. Small tornadoes that once went unnoticed are now often reported, and make the news. Gore is flat […]

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