I have just put a few charts and graphs together that hopefully clear up the misconception that seems to be doing the rounds that winds were hurricane force as storm Ellen rapidly intensified as it passed close to the weather buoy 62023 (M5) in the Celtic Sea (51.4N 7.9W) late on Wednesday evening (19 August 2020). I can see how it came about, and believe it started with SYNOP observations from Meteoceiel used by the sever-weather.eu website. As far as I know, and I could be wrong, the M5 buoy is maintained by the UKMO on behalf of Met Eireann, and because of that has always reported it’s wind speeds in knots. I think Meteociel on converting the observations from BUFR to SYNOP mistakenly thought that the speeds were being reported in MPS and so converted them from MPS into KPH. This gave the impression that the winds were almost twice what they actually were and hence the stories in the media.
On checking the plotted observations on the meteociel.fr site today they are still incorrectly plotting winds for M5. I have been watching storms for a number of years, and for whatever reason other than its position, M5 never seems to generate especially high extreme gusts. So as far as I know the highest gust was 50 knots at 22 UTC, that’s close to 93 kph and certainly not 180 kph. I suppose it’s a lesson in being careful where you access your data from, I have always used OGIMET to access my SYNOP data from and found them very reliable in their converting BUFR into SYNOP. I did run my own article suggesting rather tongue in cheek that storm Ellen may have been a very short lived tropical storm, but a category one hurricane might be pushing it a bit!
As far as I know from the WMO 306 code manual (volume 1), the 3 in the last digit of the third block that I’ve highlighted as a yellow vertical column indicates the wind are in knots.