I emailed Michael Brennan who is the director of the National Hurricane center and he responded within 2 hours. Is this good enough for you? He gives the methodology, links the data and says it is based on estimation of ground level winds based on known differences between those and airplane elevation. Then says at a later time final data will be published. Sounds above board and non-manipulative to me. YMMV
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Thanks for reaching out.
When we estimate intensity we take a variety of data into account, including flight-level and surface wind estimates from aircraft, Doppler radar data from aircraft, and satellite intensity estimates. There are also surface observations, such as buoys, ships, and land stations, but a single surface station almost never experiences the actual peak wind in a hurricane, which are often only found in a small area on the order of a few miles, especially in intense hurricanes.
For the flight-level winds from aircraft, we use an adjustment factor based on dropsonde measurements that provides a surface intensity estimate based on the peak flight-level wind (see Franklin et al. (2003)). From the typical flight level in a hurricane (10,000 ft), the reduction factor is 90% to get an estimate of the intensity of the storm at the standard "surface" height of 10 meters. The flight-level winds are averaged over 10 seconds since the aircraft is typically flying perpendicular to the flow and flies through the strongest winds only for a short time.
For Francine, the Air Force Reserve Hurricane Hunter aircraft reported several sets of flight-level winds in excess of 95 knots (we typically work in knots, which are then converted to mph). These data are summarized in a "vortex message", and I've included a couple of links below. The one just before landfall is shown below, and shows in item J. a peak flight-level wind of 102 knots that was measured at 2132 UTC (532 PM CDT). This, in addition to a previous peak flight level wind of 96 kt the hour before, both support a peak intensity of 85 kt (100 mph), which is category 2, at landfall, which was right around 2200 UTC (6 PM CDT). Our Tropical Cyclone Discussion issued right before landfall, also talks about the data used for the intensity estimate.
Note that even when we have aircraft data available, our intensity estimates are only good to within about 10%, so a system we analyzed as a 100 mph hurricane could easily be 90 mph or 110 mph based on that uncertainty. We go back and do a thorough post-analysis of all the data to come up with the final "best track", including the intensity, and will do so for Francine in the coming months, and it will be published in the Tropical Cyclone Report for that storm.
I hope this helps answer your question.
Best,
Mike
256
URNT12 KNHC 112159
VORTEX DATA MESSAGE AL062024
A. 11/21:42:40Z
B. 29.24 deg N 091.32 deg W
C. 700 mb 2894 m
D. 972 mb
E. 245 deg 7 kt
F. OPEN S
G. E36/50/30
H. 63 kt
I. 103 deg 40 nm 21:29:30Z
J. 210 deg 102 kt
K. 105 deg 31 nm 21:32:30Z
L. 72 kt
M. 268 deg 20 nm 21:48:00Z
N. 335 deg 66 kt
O. 266 deg 25 nm 21:49:30Z
P. 13 C / 3043 m
Q. 19 C / 3044 m
R. 9 C / NA
S. 1234 / 7
T. 0.02 / 1 nm
U. AF302 1406A FRANCINE OB 27
MAX FL WIND 102 KT 105 / 31 NM 21:32:30Z
MAX FL TEMP 19 C 114 / 10 NM FROM FL CNTR
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https://www.nhc.noaa.gov/archive/rec...2409112159.txt
https://www.nhc.noaa.gov/archive/rec...2409112109.txt