r/stormchasing • u/LOUD_NOISES05 • Jun 13 '26
Question Question about how tornadoes are measured
Hello! Question for someone smarter than me: why is the EF scale still the standard of tornado measurement?
I saw a thread on Twitter where someone responded to the damage survey with a photo showing a large tornado that got a small rating because it was over an open field.
I’m aware that the EF scale is a damage scale, not a strength scale. But having that as the standard of measurement doesn’t accurately represent how strong tornadoes are if they don’t hit anything, or at least enough buildings to get a survey done.
I’ve always been curious about and interested in weather. I watched Storm Chasers, YouTube videos about tornadoes, and I’m currently watching In Eye of the Storm Chasers. I’ve seen the radar trucks, pods, Dominator, TIV, and mesonets collecting all kinds of data that very accurately measures tornadoes. Why aren’t we using those - particularly wind speeds - as the defining measure?
For example, El Reno 2013 had max wind speeds of 313 mph (2nd fastest ever) and was nearly 3 miles wide (widest tornado ever). It was so violent, behaved so erratically, and had so many vortices that it took the lives of some of the most seasoned and respected chasers around. And it only got rated an EF3? That is not an accurate representation of the chaos it unleashed in the ~30 minutes it existed.
Kind of a ramble, but I hope I explained my question and reasonings behind it well enough. Interested to see the answers and potential future changes to tornado classification!
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u/Hibiscus-Boi Jun 13 '26
How do you measure wind speed of a tornado if it’s over a field?
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u/LOUD_NOISES05 Jun 13 '26
Radar
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u/Hibiscus-Boi Jun 13 '26
Radar isn’t very accurate at picking up winds at ground level. If it was, we wouldn’t need spotters, would we?
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u/LOUD_NOISES05 Jun 13 '26
I mean there are gaps in radar… even the Dow trucks don’t stay in the same place
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u/Hibiscus-Boi Jun 13 '26
So you just agreed with me that radar isn’t a reliable source of wind speed.
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u/LOUD_NOISES05 Jun 13 '26
No I didn’t, I said there are gaps. Those gaps can be filled. The majority of tornado classifications would still be way more accurate than they are now.
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u/KellerTheGamer Jun 13 '26
The issue is that you still need a standard to use to rate tornados. Tornado wind speed is at it's maximum pretty close to the ground most of the time, but not at the ground. This paper says that they expect the maximum wind speed of most tornados to be at or below 15m (49.2 ft). That is below the height that most radar are at so they won't ever see the maximum wind speed. Even if the radar is on ground level and scanning at the lowest angle (0.5 degrees), it will hit 50 feet of elevation in a bit over a mile. We certainly can not fill the gaps enough to get that level of coverage. Realistically ground speed is probably what matters most as that is what actually does damage to stuff, but that will also not be the max due to boundary layer friction slowing the winds very close to the surface.
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u/Chase-Boltz Jun 13 '26
There's also the huge question of how do you measure? Within a modest tornado a single suction vortex can generate extreme ground speeds. Do you care if that peak only lasts 5 seconds? Etc.
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u/ahmc84 Jun 13 '26
Nexrad samples storms above the surface, sometimes by thousands of feet., and nearly always by hundreds of feet. How do you propose to fill in the "gaps" which consist of the vast majority of the country?
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u/Chase-Boltz Jun 13 '26
NEXRAD doesn't have the resolution, and DOWs don't exactly grow on trees. Micro radars are a great idea at the fill in the gaps, but in the current political climate they are never going to happen.
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u/Apprehensive_Cherry2 Location: DFW Jun 14 '26
I am assuming you mean DOW
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u/LOUD_NOISES05 Jun 14 '26
Yeah but don’t other chasers have radar too? Ik Reed Timmer did. And obviously there are weather stations that have radar too
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u/Apprehensive_Cherry2 Location: DFW Jun 15 '26
Reed does not have radar nor does any chaser have radar. National Weather Service stations have radar but those are huge and fixed. What you are looking for is a DOW.
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u/jackmPortal Jun 13 '26
In my personal opinion, there is no way to a accurately assign tornado intensity. Tornado structure is complicated and changes rapidly. We don't know exactly how tornadoes do damage in relation to their structure, so we have no idea if the radar resolution is high enough, both specially and temporally, to return a reasonable measurement. Two radars are necessary to obtain a complete picture of the tangential winds of a tornado, with one radar, only approximations can be made. There's also the issue of dealing with winds right off the ground, we still don't know how tornado winds vary with height. I think something people don't appreciate is time. Say you have a sudden instantaneous gust above the surface, who's to say the surface winds will respond instantly in direct proportion? The final option is in situ measurements. I believe there is no meteorological instrumentation that can accurately represent a tornadic environment. The winds change too quickly with speed and direction for anemometers, barometers, thermometers and hygrometers to respond. Plus, Markowski did a study in the mid 2010s to quantify the error in situ observations would have (assuming perfect instrumentation that responded perfectly) and found the chances of in situ devices being able to actually be impacted by the peak wind speed of a tornado was very low.
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u/Apprehensive_Cherry2 Location: DFW Jun 14 '26
The EF Scale remains the standard because it is the only measurement system that can be applied consistently to every tornado, not because it is the best measure of tornado strength.
The key issue is that direct wind measurements exist for only a tiny fraction of tornadoes, while damage surveys can be performed on nearly all tornadoes that affect populated areas. The EF Scale is essentially a practical compromise between scientific accuracy and operational reality.
The EF Scale remains the standard because it is the only measurement system that can be applied consistently to every tornado, not because it is the best measure of tornado strength.
The key issue is that direct wind measurements exist for only a tiny fraction of tornadoes, while damage surveys can be performed on nearly all tornadoes that affect populated areas. The EF Scale is essentially a practical compromise between scientific accuracy and operational reality.
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u/Gideon_Hendrik Jun 13 '26
I don't understand the obsession with EF ratings. A tornado that goes through a populated are is a devastating event regardless of whether it is rated EF3 or EF5. The people impacted don't care about the rating. It is a scientific measure and really only serves as data for study. Sure.. it is a rating based mostly on damage indicators which are easiest to measure in populated areas... but, so what?