Are there rogue gusts?

[anoccasionalyachtsman]

Quite right. The 11 m deep channel passes at its closest less than a cablelength off. The winds are rather unrestricted by airflow from west trough south to east .

I'm not sure if you saw my post #11, but Bramblemet is also right next to a main shipping channel, and so often has its airflow disrupted by shipping and shows large spikes (both up and down) in the graphs I've linked to.

 

[kaj]

I'm not sure if you saw my post #11, but Bramblemet is also right next to a main shipping channel, and so often has its airflow disrupted by shipping and shows large spikes (both up and down) in the graphs I've linked to.

Disruption by shipping is a possibility, as brought up by you!

 

[Poignard]

I would like to know what Frank Singleton has to say about this phenomena.

 

[kaj]

Most, if not all, of us have heard of rogue waves. Few, if any, have experienced one.

Question is, do 'rogue gusts' exist?

Is the enclosed recording possibly real? Or is it just an error or malfunction? It gives a 37 m/s windburst i.e. 72 knots while the mean is 17 m/s (33 knots).

View attachment 85222

I did initially also ask the recorder, the Finnish Meteorological Institute, and got an answer today.

This recording of 37 m/s was indeed an incorrect one, which did slip trough the quality control processes. The recording has been removed.

WMO (World Meteorological Organisation) issues guides on observing, from which a (prel) extract on wind is found here.

 

[Frank Holden]

Microbursts are a well known danger to aircraft; these are caused by sudden cooling of air by rain, causing the air in a small area to drop downward suddenly. When the downburst reaches the ground, it then spreads out sideways. Apparently that can be of very short duration - seconds to minutes - and be powerful enough to knowck trees down.

BTW, just to reiterate that katabatoic winds aren't a factor in the UK; they result from intense cooling of air at the top of a topographic feature (e.g. over a glacier or ice cap in high mountains). The cooling makes the air more dense so it flows downhill. They are typical of large ice-caps such as Antarctica and Greenland, or smaller ice caps such as those in the southernmost parts of the Andes where there is a drop from glaciers at high elevations to sea-level in a short distance. In Antarctica they can result in persistent winds of over 100 knots for weeks on end!

The worst rachas I have experienced are in the western end of Estrecho de Magallanes when you have a strong SW in the Pacific pushing dense air over the top of Isla Desolacion... about 1000 metres or so high. This dense air comes off the land, finds itself at altitude with no visible means of support, and so just drops... landing as microbursts maybe a mile or so offshore. At the time you will typically have about a 15 or 20 knot NWly blowing in the strait. Similar conditions can be found south of Cabo Froward with a north wind blowing.
If caught with sail up you would have a good chance of being dismasted.

 

[boatmike]

Dunno about all the scientific stuff but I live in Lee-on-Solent. In the recent storm I was recording a steady 55-60MPH and gusts of up to 80MPH then one gust went right off the scale of my little monitor, rattled all my roof tiles and took the roof off my dormer competely. Never did find it. Probably now somewhere in Essex........ Does that qualify as a "rogue" ?????? I called it a "fuckit" .........

 

[TSB240]

I think this was a little "rogue gust"last Sunday am post Dennis. Friends boat took some damage in Victoria Dock.
Helen Owen
And from Caermarfon castle viewpoint

https://www.facebook.com/436306583398084/posts/1057573074604762

 

[misterjenkins]

Not as extreme as the gust posted by the op, but we encountered something similar sailing past East Head on our way to Itchenor. Took this screenshot from Cambermet when everything calmed down. Very noticeable drop in wind speed and change in direction before it hit. We were running down wind at the time, but saw 43 kts apparent onboard. Quite surprising.

 

[webcraft]

.
I had a gust of 54 knots when sailing off the coast of Tenerife in 25 knots in the Canaries. I believe it was a downdraft off Mt Teide. It was certainly interesting . . . we were sailing downwind under full genoa at the time,. The genoa gybed itself and the boat took off like a scalded cat, nothing to do but hang on until it subsided.

I have also experienced several gusts of over 50 knots in Whiting Bay, interestingly when I was trying to demo 'man overboard' to a group of Day Skippers. The exercise had to be abandoned, as it proved to be beyond even my skills in those conditions.

A friend was also knocked down sailing between the St Kilda stacks in otherwise quite manageable conditions.

So yes, there are definitely rogue gusts, but most of them are probably associated with terrain features. Interesting to know if anyone has experienced such gusts in open water more than ten miles from land.

- W