Forwarding this to the right thread, but I find it bizarre how many 140-150mph EF3 ratings have been applied to residences that were leveled/swept away this year. The lower bound for a residence that is swept clean is 165mph, yet homes like the bolted ones in Bakersfield, Missouri and Lake City, Arkansas were given 140mph and 150mph respectively. This South Dakota tornado flattened and swept away a farmhouse, albeit poorly anchored, but was given a 150mph EF3 rating. Just misapplication of the scale.
Yes, this is something I’ve noticed as well and is most certainly quite odd. We’re now going
below the supposed lower bound on a lot of the DoD for these structures and it makes little sense. Just another inconsistency with the scale, which is easily its biggest issue IMO. It’s just ludicrous to believe that Plevna, Grinnell, and Lake City are weaker than Little Rock 2023 or Sulphur 2024. Tornadoes which were rated completely fine from what I can tell. Lake City is especially awful to me, and I believe that’s the worst rating this year easily.
I mean, I think the reasonable conclusion to these bolded points is that we're rating those contextuals way too low, and not that lower winds somehow managed to defy physics and do the impossible. Sub 200 mph winds tossing that train car is mathematically impossible. We've never even bothered to study or understand contextual indicators like debarking or scouring, and we toss them out as irrelevant whenever they're all alone, but then we use them as evidence for downgrades when they're next to structures we can actually calculate with a high degree of certainty? It makes zero sense.
This is a fair point, however I do have to say that I’m operating under the assumption that the calculations being done are always overly idealized in the sense that they’re
1. Assuming that the force from wind is uniform in both magnitude and direction a lot of the time,
2. Don’t take into account what the structure’s condition was at the time of the tornado impact, unless evidence proves otherwise, and
3. Don’t take into account other factors that may contribute to damage, whether we know about it (the so-called “swirl ratio” that I don’t fully understand myself just yet) or not.
None of these points are problematic either with maybe an exception to 2, simply because if one of these were not implemented to our calculations, they become nontrivial to solve at best and practically impossible to solve at worst. Unless we figure out a new way to approach these things.
I’ll throw an example of my second point here. Imagine there’s a home that is built in 2023 and it’s initially exceptionally well-built, but no one moves in and it gets a termite problem that completely destroys the integrity of the structure and goes undocumented (or poorly documented). Then, a year later, an EF3 tornado comes in and completely slabs it, but the surrounding contextuals of the house aren’t strong. Surveyors would be operating under the assumption that the home was indeed well-constructed - and it’s slabbed, so that’s at least an EF4 right? Obviously not, given the context of the home, but surveyors wouldn’t know that. The only clues they would have that the home wasn’t well built at the time of destruction would be the poor contextuals.
This, IMO, is a fair reason to err more on the conservative side of things rather than the liberal side of things, because things like this are absolutely possible. Note that this is just an example and I don’t think this has ever occurred, but replace the termite problem with any other issue that may degrade the structure’s integrity before a tornado and the same logic applies. Also, there’s obviously the side of being
too conservative, which is the issue we’re facing today with a lot of WFOs. That’s the bulk of my argument, at least, and there’s probably more I could bring up but that’s pretty much it for the time being.
