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
Read more at Not A Lot Of People Know That
3 pm – NOAA still showing Humberto as cat3
https://www.nhc.noaa.gov/storm_graphics/AT09/refresh/AL092019_5day_cone_no_line_and_wind+png/175228_5day_cone_no_line_and_wind.png
https://www.ventusky.com/32.057;-67.100
highest wind speed 10 m above ground = 88 mph
Noted same disparity with Dorian winds too.
Just checked Humberto as reported here… @ 5 a.m. EDT today.
https://www.accuweather.com/en/weather-news/humberto-to-track-dangerously-close-to-bermuda-possibly-as-a-major-hurricane/534497
Humberto reached Category 3 major hurricane strength on Tuesday night as it tracked closer to Bermuda. The powerful hurricane is expected to skirt just north of the islands with rain, wind and pounding seas.
As of 5 a.m. EDT Wednesday, Humberto was located about 285 miles west of Bermuda and moving east-northeast at 16 mph with maximum sustained winds of 115 mph with higher gusts. A hurricane warning is in effect for Bermuda.
The hurricane is expected to turn fully to the northeast into Thursday.
Highest speeds at 10 m and 3000 m as follows…
https://www.ventusky.com/?p=31.324;-69.657;9&l=wind-700hpa&w=strong
highest reading 112 mph 700hpa, 3000m
highest reading 104 mph 10m above ground/surface
I was looking at: https://earth.nullschool.net/#current/wind/isobaric/10hPa/overlay=temp/orthographic=128.06,82.07,309/loc=-112.119,35.719
Ran the pointer over the eye at various altitudes and distances from the eye-wall for several days. Found the highest wind speeds at 700mb – roughly 10,000 feet. Highest spot reading: 174 Km/hr. I have no idea how accurate that service is – but I sure didn’t see the speeds reported in the media.