I don't have any special insights, all I can say is that I read the relevant literature when those that called it pseudoscience usually had not (and even if something is wrong, that doesn't make it 'pseudoscience' specifically). It's based on assumptions that are reasonable, if not strictly correct, and a reliant on geometry that doesn't particularly special (though I couldn't do it myself, but I'm increasingly realising that my school maths education was actually appalling and missed a lot of useful things).
There are some unanswered questions I think are worth considering:
- The method assumes that the marks are produced from a point, but it's not clear to me from simulations that's actually the case. The issue this raises is whether the marks are representative of windspeed at all.
- The method assumes that the marks are regular, i.e. that both the speed relative to, and distance from the centre are steady. Both the fact that real-life marks are often visibly distorted, and tornado simulations show that neither of these assumptions is true (which is what Fujita was trying to get around when he studied the 1965 Greentown tornado). How much does this matter?
- Most analyses I've seen correspond to EF-scale windspeeds. However, the marks are generated at very low levels, so it's not clear how these correspond with standard gust values (i.e. 3 seconds at ten metres or similar). The modelling I've seen on ground marks was on a metre scale, but something on a significantly finer scale would be more informative.
That said I don't think the assumptions and unknowns are tremendously more problematic than some of those behind EF-scale damage analyses.
