Yes, that was very interesting! Moreso because it was one of those serendipitous things that I happened to catch when I wasn’t really looking for it (like staying up and so seeing the recon report from the flight that went into Wilma at 850 mbar, to find a pressure of, I think it was, 902 mbar, in October 2005). I had checked Chebi earlier in the evening, then looked later on and was surprised to see that it appeared to be organizing rapidly.
What I didn't (still don't) understand is why they didn't go with the data T-number (6.5). AFWA did. And why winds were not as advertised in landfall at Luzon, but weaker. I've been puzzling over it, but haven't had any time recently to go back and look at the satellite imagery.
Either it did intensify that much, and weakened before landfall, or the satellite signature didn't really match the actual windspeeds. Why that would be, I don't know, but it seems like a possibility. Perhaps there was a steady intensification up until landfall, rather than the quick intensification followed by weakening, as far as windspeeds: the apparent rapid pressure drop, as a small well-formed eyewall quickly developed, was followed by a decrease in organization prior to landfall, as the eye clouded over and the convection became less symmetrical. Maybe windspeeds didn’t have time to catch up to the pressure drop before the downturn in organization that appeared on the satellite images, but were only able to increase somewhat, and then continued increasing at a slower rate prior to landfall, still catching up to the pressure.
On the other hand my initial impression had been that there was some weakening before landfall, looking at the outflow (if you try to find other things to go by besides the eye and convective structure). It's harder for me to look at the convection in the West Pacific and get a feel for it, since cloud tops run colder there.
The drop in pressure that was associated with the satellite intensity estimates was, I think, 57 mbar over the six hour period. I'd initially seen a post by a met on storm2k that was titled "40 mbar drop in two hours," (they kept updating the title of the thread, so I think it now reads dissipating in the South China Sea or something like that), but since then, looking back, I don't think it could have been that dramatic.
I also don't know if there were any reliable wind measurements close to the center at landfall, or if windspeeds could be estimated from damage. The lack of damage from Chebi could be in part due to the previous two cyclones already taking down all the trees and buildings that would have come down in a significant storm. Also it appeared the core of stongest winds was very small, and may not have been observed at landfall (like Monica earlier this year).
Simone
