Dorian joint second most powerful Atlantic Hurricane on record

[xmetman]

I forgot to post these latest stats on Hurricane Dorian yesterday. 

Of course they're based on provisional data but are unlikely to be amended.

It has the joint second highest sustained wind speed of 160 knots.

But only the joint tenth lowest central pressure of 910 hPa.

[xmetman]

Hurricane Dorian passed relatively closely to NOAA buoy 41010 overnight as it was making its right turn up the eastern seaboard.

Mean speeds and gusts were pretty high as you would expect, as too are wave heights.

Not a time to be out at sea in a boat.

It's a shame that animated GIF's no longer seem to be allowed which is annoying because it works so well in the editor...

[xmetman]

I see Dorian is now appearing on the forecast charts for Sunday when it looks like Newfoundland will be getting quite a stormy day.

[Graham Easterling]

Please don't think I'm in anyway belittling the devastating affects of Dorian, but I'm often a little surprised the wave heights aren't greater. 

A significant 10m wave height (SWH) in the north Atlantic would be nothing exceptional, occasional sets would contain waves 50% bigger. Even just off west Cornwall at Sevenstones, 

"Significant wave heights at Sevenstones with return periods of 50/10/5 years are approx 13/11.5/11 metres. The big sets would be 50% bigger

North Atlantic depressions clearly don't generate the same wind strength, but you can have a F10-11 persisting over a long great circle route, allowing the wave to build over an enormous fetch. In fact the highest monthly average wave height, anywhere in the world, is just to the W/SW of Ireland in January.

Individual 10m sets occur virtually every year off west & north Cornwall (the coast the waves following a long great circle route hit). 

The issue with hurricanes (apart the wind!!!) is the surge much more than the swell height. The small area of severe winds, combined with the curvature of the isobars, generates an horrendous sea, but not the swell height you might expect.

1 of my photos of an 8-10m wave approaching Sennen breakwater on a fine February day, a day forecasters wouldn't consider mentioning the sea conditions.

That's the lifeboat slipway on the left, imagine having to launch the lifeboat into that, it would look like a toy.

Surfing a 6-7m wave at Newquay (not my photo).

Graham

Penzance