Hurricane Dorian’s 185-MPH Wind Speeds Don’t Stand Up To Scrutiny
I have some updated data for Hurricane Dorian which is relevant to my earlier post, Hurricane Dorian–The Facts v The Myth.
Just to recap from that post:
1) Claims of 185 mph winds were based solely on hurricane hunter aircraft data.
2) Based on the central pressure of 910 MB, wind speeds would be expected to be 165 mph. This is how wind speeds were calculated prior to aircraft and satellite data.
3) Satellite data for Dorian indicated winds of about 140 mph.
4) The figure of 185 mph appears to have been derived from Stepped Frequency Microwave Radiometers (SFMR), which are known to artificially increase wind speeds in areas of shallow waters, such as are present around the Bahamas.
One reader got hold of the dropsonde data, which appeared to back up the SFMR readings:
This is the data from the dropsonde when the storm was at its peak. (To replicate it, you need to use the decoder):
However, there is a big problem here.
Wind speeds used under the Saffir Simpson scale must be 1-minute sustained speeds. Given that dropsondes are falling at a rate of about 3,000 ft per minute, clearly they can only measure peak winds, as the dropsonde data page actually states:
Wind gusts can easily be 40 mph greater than sustained speeds, so the data from the dropsonde is essentially worthless for deriving the latter.
It does appear that the National Hurricane Center are keen to paint the worst picture every time a hurricane comes along, for whatever reason.
Every single fact about Dorian, however, suggests that it was less powerful than the official reports have made out.
References
1) The NHC dropsonde archive data is here:
https://www.nhc.noaa.gov/archive/recon/2019/REPNT3/
2) The decoder is here:
http://tropicalatlantic.com/recon/recon.cgi?page=decoder
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