“I just saw a tornado!”
That is a message I receive almost every other day from viewers. Doesn’t matter the weather. Doesn’t matter the time. Social media has made this kind of message easier to send. And receive. It is a terrific resource during severe weather events. And I’m thankful for every report I get.
But, almost every time, it is a false alarm.
In fact, I have only received about a dozen reports of a tornado from viewers that have ended up being verified. And, after receiving no less than about 500 messages claiming to have seen one, only to have about 10 verified, one can imagine I’ve become numb to reports on days when tornadoes aren’t anticipated. Or statistically significant.
I don’t fault the viewer, though. Clouds can be tough to identify. Clouds move around, condense in weird shapes, have tornadic-looking features, and during bad weather can be really dark and ominous-looking.
Tornadoes in July: Quite improbable, though not impossible
I try to always take some time to explain to folks what they might be seeing instead. Last Friday I did exactly that. I went outside while a shelf cloud rolled by the television station. I wanted to show folks – on a regular summer day – how clouds might look one way, but are most likely another.
Before this July, the last tornado in July was in 2000. It was in Pearl River County. An F-0 that was about 10 yards wide and was on the ground for about 200 yards. The time before that? The 1960s. Same idea, too. An F-0 that was 10 yards wide. On the ground for about 200 yards.
Summer storms don’t have the ingredients needed to produce tornadoes like the big ones we see in the winter and spring. In fact, in order to spin up a tornado in a summer storm there often needs to be multiple intersecting outflow boundaries under a developing storm. And getting that to occur is pretty unlikely, too.
The three July tornadoes:
| DATE | COUNTY | STRENGTH | WIDTH | PATH |
| 07/22/00 | PEARL RIVER | F-0 | 10 YARDS | 0.10 MILES |
| 07/20/66 | MARION | F-0 | 10 YARDS | 1.00 MILES |
| 07/06/65 | FORREST | F-0 | 10 YARDS | 0.10 MILES |
These July tornadoes just don’t happen often. And when a tornado does, it is brief and quite weak. The ingredients are just not there in the summer to build a tornado. For south Mississippi, there were a total is 554 tornadoes between 1950 and 2015. But of those 554, only above-mentioned three occurred in the month of July.
That in one-half of one percent of the total number of tornadoes.
But, really, the chances of a tornado in July get even slimmer. South Mississippi usually experiences three to nine storms per day, on average, in July. Some days there are no storms, others there are more than 20 individual cells in a 24 hour period.
For the sake of argument, and some quick math, let’s say on an average July day there are six storms. Time for some quick math…
| 6 Storms | x | 31 Days | = | 186 Storms |
| 186 Storms | x | 65 Years | = | 12,276 Storms |
| 12,276 storms | / | 3 Tornadoes | = | 0.000244379 |
| Probability of TOR |
That means, historically speaking, there is a 0.02 percent chance that any one summer storm produces a tornado. So, when I receive one message, almost every day in the summer from folks telling me there is a tornado in a storm, I hope folks can understand my skepticism (Note: I also get reports of tornadoes when no storms are present on radar).
July Tornadoes in 2016: Improbable, but adept at surprise
That led to a brief moment in the video above where I wanted to reassure folks that in July tornadoes aren’t likely. And why I say that I can almost guarantee there wasn’t a tornado.
Here is that snippet:
Again, I want to reiterate that I appreciate everyone that reports a tornado. Truly, I appreciate any and ALL reports of any weather. But my skepticism of a tornado – in July – has little to do with the person that reports it, and more to do with the statistical likelihood of a tornado existing.
If a carpenter built 15 chairs per year for 65 years and only three ever broke, would anyone be worried about sitting in one of those chairs? I would hope not. For 65 years, southern Mississippi has experienced about 15 tornadoes per year. Only three – ever – were in July.
So, imagine the surprise to meteorologists when in 2016, so far this July, there have now been two confirmed tornadoes. Both stronger and much larger than any recorded before.
The 2016 July tornadoes:
| DATE | COUNTY | STRENGTH | WIDTH | PATH | LENGTH |
| 07/11/16 | JEFF DAVIS | EF-1 | 200 | 0.77 MILES | 5 MINUTES |
| 07/23/16 | JONES | EF-0 | 100 | 0.86 MILES | 5 MINUTES |
The first was believed to be a statistical inevitability. After a 16 year window of no tornadoes in July one was bound to occur at some point. But an EF-1? And 200 yards wide? And now a second tornado? Wow.
But this time someone said there was one!
In the case of the second tornado, and the videos above, folks are frustrated that I would quell messages on the Facebook Live video of a tornado. Some folks believe I acted arrogantly and I was accusing them of lying to me.
That is not case, I assure you. There was no accusations of lying in the video – or anywhere. And my attempts to suggest straight-line winds rather than a tornado was based on available radar information, historical statistics, and forecast data – as well as the numbness I’ve likely built given the repeated number of false reports.
There were no reports given to me of any trained spotters reporting a tornado. There was no word from the National Weather Service of a tornado, either. The radar data showed a very broad area of rotation as two cells merged, but one that wouldn’t be likely to produce a tornado even in the spring, when we expect tornadoes to form.
Maybe a useful analogy here… If you have five kids and four of them said the fifth child made a mess on the carpet. But the fifth one said the others did it, who would you believe at first? Perhaps later it turns out the other four did it, sure. but your immediate reaction would be to believe the four rather than the one.
Plus, it would be irresponsible of me to simply repeat every report that is given to me without vetting it properly. If I were to do that, you would likely hear me warn you of tornadoes almost daily. It would become a game of “The Boy Who Cried Wolf” on the news. No on wants that.
So what about next time?
Honestly, I will likely do the exact same thing. There was a Severe Thunderstorm Warning issued by the National Weather Service in Jackson, Mississippi for that storm at the time. The warning was for winds gusting more than 60mph. And, that verified. When a Severe Thunderstorm Warning is issued, we always suggest heading inside and finding a place to be while the storm passes. Straight-line, non-tornadic winds can do just as much – and sometimes more – damage than a tornado.
And, really, any storm given a “Severe Thunderstorm” warning is capable of producing a tornado.
So, we always hope that you don’t ever say “It is just a Severe thunderstorm Warning…”
And when you say, “I just saw a tornado!” it isn’t something I take lightly. But, it is something I want to make sure is legitimate before I pass along to others. Because I know that when someone at WDAM says it, none of you take it lightly. At all.
UPDATE: Thoughts from a National Weather Service meteorologist via facebook
