Q&A: Leading tornado researcher discusses western Kentucky scene
National Weather Service storm surveyors are still working this week to determine just how strong the tornadoes were in western Kentucky over the weekend and how many of them touched down.
The National Weather Service has brought in several teams and experts, including Tim Marshall.
Marshall is one of the principal researchers into enhancing storm warnings and the scale used to determine the severity of storms and tornadoes. He is a civil engineer and meteorologist whose interest in tornados began at a young age when his hometown was hit with a, then categorized F-4 tornado in 1967. Marshall was on the ground in western Kentucky assessing damage shortly after the tornado system moved through the region.
WKMS News Director Derek Operle interviewed Marshall by phone Tuesday.
Operle: So Tim can I ask you, when did you first start following this storm system? Were you aware of this earlier in the week?
Yes, I was. During the event, I followed it minute by minute and watched the radar from my house for hour after hour as this thing marched through Kentucky.
Operle: When did you come to western Kentucky and where did you survey the damage from?
I flew in the next day and surveyed on Sunday in Mayfield and Monday in Dawson Springs.
Operle: Can you distill in layman's terms what made this storm system so strong?
A lot of the ingredients came together. You know how warm and muggy it was in Kentucky that day. The dew points were high so there was a lot of energy there in the atmosphere and we had a strong upper system coming in from the west and on top of that we had a strong jet stream which helps ventilate the storm. So you had the moisture which is the food for the storms and you had the jet (stream) aloft which evacuates the top of the storm and pulls in the strong updrafts. So we had all the ingredients coming together for a major event.
Operle: Tell me aside from atmospheric conditions, what allows for tornadoes to stay on the ground for such a long track? This tornado was obviously on the ground for, at this point they’re saying, at least 200 miles in Kentucky alone.
Yeah, this is a historic event. And what makes a storm reach what I would call a steady state where it produces a violent tornado and remains that way consistently for over 100 miles, like you say? So that is going to be studied for years to come to determine what makes a storm like this. You think of tornados as being very fleeting – they’re there and gone in just a minute or two but this one stayed on the ground, like you said, for a long time and we want to know why that was.
Operle: You’ve tracked more than 300 tornados in your life so far and our governor obviously is saying this is a storm of historic proportions. Tell me, aside from how long this storm stayed on the ground, what makes this historic?
Well certainly we have a track length here that could be historic. How many tornadoes in history have gone over a hundred miles? It’s very few. The Tri-State Tornado, as you recall, was just a little further north and it stayed on the ground for a long time and this will maybe even exceed that and become the number one event in terms of the length of the track.
Operle: You’ve been pretty active on social media with photos and commentaries in the wake of the storm. We read one interesting comment asking if bark had been stripped off of the trees. Is that part your normal damage assessment and what would that indicate if it were?
Well we want to look at any unusual items along the path. I’ve documented some of these missiles – like a tree branch through a tire for example and then we had a refrigerator in a tree in Dawson Springs. The refrigerator was intact. I mean it wasn’t dismantled. The doors were still on it. So there are some very unusual things like this happening. When you get a lot of debris flying around you can strip trees of their bark. I’m sure there’s some of that out there. My concentration was in the towns rather than out in the country but I saw driving in a lot of tree damage where it looked like somebody had just mowed down a forest.
Operle: A large water tower collapsed during the tornado. Is that a structure that you would normally expect to withstand a strong tornado like this?
Well you know it all depends on how it’s built and how it’s designed for. Now I doubt seriously that the water tower was designed for a tornado of this high intensity impacting it, but I wanted to find out since it was a newer water tower and a substantial water tower. I wanted to find out how this was attached to the ground in the foundation. We want to look at these failures. We learn by these failures. So that’s what I did. I went ahead and evaluated and I found some things I was not too happy with in terms of how it was attached to the piers. Again, I don’t know what the design was for but these high-end tornados certainly can take down such things.
Operle: So in your surveying what level of damage were you seeing? Do you think this was indicative of an EF-3 or EF-4 tornado or do you have some kind of preliminary rating before the surveying is finished?
Well you have to keep in mind I only looked at the two towns and there are many towns that were affected and many rural areas were affected as well. So I only looked at some spots that were the higher ends – the EF3s and 4s out there – and the (National Weather Service) obviously needs to cover a lot of those more extreme areas so they’re still out and they’re still assessing the damage. More information is coming in daily to see what happened. I could only spend a couple of days there given the fact that I have other commitments going on right now but the weather service is continuing to evaluate this and you’re going to see updates as the days progress.
Operle: So you haven’t seen or heard anything indicative that this was close to an EF-5?
Well we have many locators that everyday are coming in. New locations saying look over here. One place is near Bremen and there’s a train that went over in another location so there’s several areas coming in daily and those are being checked in by my replacement.
Operle: As the Mayfield community looks to rebuild, what are some building practices you would recommend?
Well of course buildings are one thing and another thing is occupant safety. I’d like to see more in the way of sheltering people. No way is a building going to be able to survive these violent-end tornados because they’re not built to that. They’re built to kind of a standard of around 90 miles per hour and these winds were much greater than that so these buildings are failing. So the heck with the building let’s talk about saving peoples’ lives inside and maybe having a hardened area inside buildings – some sort of a shelter where people can go and they can survive.
Operle: Do you see evidence of increasing frequency and severity in recent years?
I haven’t. I look at these violent tornadoes once or twice a year. That’s typical. And this year I have not been on a survey. So this is actually my first survey of the year.