You're listening to Shortwave from NPR.
Hi, Shortwavers.
Emily Kwong here with producer Hannah Chin.
Hey, Em.
Hey.
And we have been working on an episode for a listener who has been with us from the very beginning.
I think back to episode one.
This is Barry Zalf.
He lives in Louisville, Kentucky.
Though I don't remember what the episode was.
That's because these days, Barry's thoughts are much more consumed by a shift in his daily life.
Namely, the wind.
I just have a personal perception that it has gotten considerably windier in Louisville over the 35 years that I've lived here.
We're getting lots of wind on dry, clear or partly cloudy days that we would have never seen before, when there wasn't a thunderstorm happening, which really bothers Barry because he likes to bike.
And, well, wind isn't great for bikers.
But to truly figure out whether it was getting windier.
Barry did what any good science journalist would do.
He went digging for data.
And over Zoom, he showed me over 20 years of NOAA data about Louisville's wind patterns.
Share.
Can I share a screen?
I love that our listeners make graphs for their questions.
Yeah, it's so good because he wanted to make sure this wasn't a recency bias, because Louisville has seen a few windstorms in recent years.
But when I looked at his data across 20 or so years.
For every measure, the wind speed is higher for the last 10 years of my data set than for the first five years of my data set.
And that impressed Scott Gunter.
Does Barry want to come back for a graduate degree or something?
Like, holy analysis, that is awesome.
A few notes maybe, but in general, like, that's really impressive.
So this is Scott Gunter.
He's an assistant professor at the University of Louisville with a special focus on extreme weather.
And he was excited to see this graph, because low-speed winds aren't really something a lot of scientists pay attention to.
Researchers like Scott are more worried about severe winds, which the National Weather Service defines as winds above 58 miles per hour.
They're the kind of winds that can cause damage.
But here's the thing.
We all grapple with low-speed winds in our daily lives.
To Barry's point, they can be totally disruptive to us as humans, even if they're not turning into high-speed tornado winds or toppling buildings.
Today on the show, we interrogate the wind for Barry.
Scott helps us dig more deeply into wind, how severe winds and thunderstorms unfold, and asks the question whether Tornado Alley is shifting as the climate warms.
I'm Emily Kwong.
And I'm Hannah Shin.
You're listening to Shortwave from NPR.
Okay, Scott, so wind is just moving air.
How does wind get around and how does it get around so fast?
There's one force in particular that really drives wind, and we call that the pressure gradient force.
Huh. it's just changes in atmospheric pressure.
And we live at the bottom of an atmospheric swimming pool.
Just like if you dove underwater in a pool.
You can feel that pressure of all that water pushing down on you.
I almost think like we have an ocean above.
Yes, a thousand percent.
With like currents and pressure gradients.
Yeah, you got it.
And there are areas of high pressure, low pressure that are approaching one another or interacting with one another.
If we think about an area of low pressure, that is typically an area of rising air.
That rising air causes other air to flow inward toward it.
And then that leads to a whole other array of atmospheric interactions that lead to thunderstorms and rain.
And so areas of low pressure are stormy and windy, while areas of high pressure are less windy and kind of clear skies, not stormy.
What drives changes in wind patterns over time?
So those areas of low pressure are essentially being driven by the jet stream.
This river of very fast moving winds way, way above our heads, top of the troposphere.
That's essentially our storm track.
And that's one reason why Kentucky sees a lot of that is we're part of that storm track.
A lot of areas of low pressure form in Texas and Oklahoma.
Yeah. scoot right up the Ohio Valley into the Northeast.
And one of the things that we're kind of expecting to see down the road with climate change is a shift in that jet stream to maybe be further north.
Ah.
That would suggest maybe that in time it would become less windy here, just like places further south.
Wow.
So the positioning of the jet stream is very important in terms of driving these synoptic windstorms.
Gotcha.
Okay.
I want to dig deeper into Barry's question.
Just moving from his graph into what you know from your data, is it getting windier in Louisville?
So overall wind is very dependent upon larger atmospheric circulations, where wind speed maybe increases for a few decades and then maybe decreases a little bit.
And so it's hard to tell if that is a long-term trend.
Or maybe a shorter decadal trend, multi-seasonal trend that often shows up in climate data.
And I will give Barry full props for using almost what we call a climate normal, which is a 30-year period.
And so the longer that you can stretch out that period, the better that you can understand some of these trends and see whether or not this is long-term, like climate scale, or is this a short-term weather phenomenon, such as Maybe the effects of El Nino or La Nina or something like that, that is causing kind of some of these spikes that affect the trend?
If you were to look at that graph without Barry's own interpretation, what would you gather from it?
I probably would have come to the same conclusion.
It looks like the more recent years have had a greater number of wind speeds above specific thresholds.
But overall, we are not seeing an increase in extreme winds and high winds.
Correct.
However...
Barry, what he's seeing, at least with the data he gathered from Bowman Airfield, does suggest an increase in, like low winds.
Yeah, lower intensity winds.
And I thought that was really kind of a clever way of looking at that, because meteorologists we're usually focused on extremes.
And a lot of the research suggests that extreme winds.
There hasn't been much change through time in the eastern part of the US.
And so this was really kind of interesting to see those lower wind speed thresholds.
And I am not sure how much that's been explored in science, the literature and you know, from a peer reviewed perspective.
Totally.
The winds that only a biker would notice.
Right.
And you're currently working on a project that measures weather, including faster winds, in Kentucky overall.
Have you seen any noticeable changes over the last 30 years?
There has been. maybe an arguable uptick in some of the sustained winds.
And as I was thinking about this and this kind of connects to even what Barry was seeing, whereas our wind gusts kind of have not necessarily seen that same pattern.
And I think this is where it does get difficult and it's always worth reiterating this idea of weather versus climate.
And trying to pull out specific weather events from large-scale climate data sets is kind of tough.
Maybe in another two years, I'll have a more direct, less...
You're working on it.
Yes.
Yeah.
A more direct, less kind of wishy-washy answer for you, but... This is the process of science.
You gather data.
It takes a very long time.
You have to be very rigorous.
You find out.
Kentucky is not Tornado Alley.
When people think of tornadoes, they don't think of Kentucky.
However...
I've been Googling and there's all these articles saying, will Kentucky be in tornado alley?
Is tornado alley moving east?
What do you have to say about Kentucky and tornadoes?
Excellent question.
So when we talk about things like tornadoes, um, we generally portray them like cupcakes.
So, in order to make cupcakes appear, you have to have all the ingredients at your house, in your kitchen, and then you have to mix those ingredients together in order to produce a cupcake that's going to sit on a very specific place at your counter.
So with Tornado Alley, or this idea of Tornado Alleys, we're basically highlighting these regions where the ingredients come together relatively frequently.
A tornado can happen anywhere, anywhere those ingredients come together.
And so what we're seeing, I think, is maybe variations in where those ingredients are coming together.
And there could be a lot of different things driving that.
We can say in the future that with climate change, the ingredients may come together more frequently in places they haven't come together before, like this shift that we're seeing in Tornado Alley.
But we can't necessarily say anything about tornadoes themselves.
Those are weather events.
They're too small scale to project those out into the future.
But there's a lot of excellent, excellent research going on looking at the severe storm environments, the environments that tornadoes form in, and how will those change in the future.
And that will be certainly very important for preparedness, because to live through a tornado is not a cupcake-like experience at all.
It's very well put.
Scott, thank you so much for coming on Shortwave to talk through all of this with us.
Oh my goodness, Emily, this has been great.
I've enjoyed this so much.
And thank you to Barry Zalf for listening to Shortwave from the beginning.
Be like Barry and follow Shortwave and send us your questions about your local environment.
We'll take a crack at it on a future episode.
Our email is shortwave at npr.org.
This episode was produced by Hannah Chin and Noor Gill.
It was edited by our showrunner, Rebecca Ramirez, and fact-checked by Tyler Jones.
The audio engineer was Jimmy Keeley.
I'm Emily Kwong.
Thank you for listening to Shortwave from NPR.
