On the hurricane side, my impression is that many hurricane chasers overestimate winds-- sometimes very generously.
For example, on the leading, weaker side of Hurricane Wilma, one of my companions described the winds as "over 100 mph". But almost all of the trees in the nearby parking lot were still standing, so the estimate seemed extravagant. I think the winds were perhaps gusting to 60 or 70 kt. (Note: Winds were much more severe later,
after the eye.)
In another example, I saw video footage from an experienced chaser who estimated the winds at 110 mph. But the footage showed his friend walking (with difficulty) in those winds, which would not be possible at 110 mph. Furthermore, cheap-looking strip-mall signs in the shot were not getting blown out. To me it looked more like 50 or 60 kt-- and when I compared the chaser's location with the HRD wind swath, my estimate was pretty close.
Generally, I'm pretty conservative in my estimates. I find it very difficult to estimate winds
while they are happening-- I don't have enough experience and the Beaufort scale seems very subjective, very difficult to apply.
To get a very rough, ballpark idea of wind speeds
after the storm has passed, I base my estimates on observed damage according to the Saffir Simpson scale-- in the same way that one uses the Fujita scale to class a tornado based on damage. For example, if there are lots of trees blown down and signs blown out, some broken windows, and plentiful examples of roof surfaces and/or small portions of roof removed (but no complete unroofings), I would correlate that with high-end Cat 1/low-end Cat 2 and estimate max winds around 80-85 kt. The Saffir-Simpson scale wasn't meant to be used this way, but since I haven't had any formal training for estimating winds, this is the best I can do.
