Strange wind in R Stour

[Dan Tribe]

We were coming past Halfpenny Pier this morning, reaching on port with a south easterly. A boat about 200 metres to our starboard picked up a north west breeze and pulled away close hauled on starboard on the same course as us. I expected we would soon get the same but we held the south easterly all the way to Ewarton. I could see boats up by Wrabness had a westerly breeze but below Ewarton it was easterly. This stayed constant all day. Is it often this weird here?

 

[pvb]

Yes, strange things happen in the Stour. Really best to avoid the river altogether.

 

[nortada]

Yes, strange things happen in the Stour. Really best to avoid the river altogether.

Especially if you are a witch

 

[photodog]

We were coming past Halfpenny Pier this morning, reaching on port with a south easterly. A boat about 200 metres to our starboard picked up a north west breeze and pulled away close hauled on starboard on the same course as us. I expected we would soon get the same but we held the south easterly all the way to Ewarton. I could see boats up by Wrabness had a westerly breeze but below Ewarton it was easterly. This stayed constant all day. Is it often this weird here?

It did seem particularly weird yesterday.... there was a definite SE / Westerly split with a dead space in the middle were the big yellow ships mooring is.... held for me until about 1500 ..... by which time I was back off harwich with a good SSE.

Good day.

 

[Chalk]

Same in the Wallet yesterday too off Clacton. Most bizarre. Wind backed from NE to west in the space of a mile or so.

 

[MikeBz]

We sailed from B’sea to the Backwaters on Friday pm. Started out with a lovely warm North-Westerly as per the forecast. Approaching Clacton pier it went to NE in the space of a few minutes with a big temperature drop, wind on the nose the rest of the way - not forecast at all. Then yesterday coming out of the Backwaters in the light NW that was forecast for the day, in the space of a few minutes it went round to a solid SE which persisted until well into the evening up in the Deben at least - again this was not forecast at all.

 

[scruff]

I've seen two boats, sailing towards one another going in opposite directions both under spinnaker in the sound of Mull!

 

[Dan Tribe]

So what happens to the airstream in such a convergence? Does one bounce over the other or both go vertical ? Having trouble visualising it.

 

[AntarcticPilot]

Could it be opposing sea breezes from opposite banks of the river? That would give a downflow of air over the middle of the river and upwelling over the opposing banks.

 

[johnalison]

Could it be opposing sea breezes from opposite banks of the river? That would give a downflow of air over the middle of the river and upwelling over the opposing banks.

I think the SE breeze set in quite early in the day, before one would have expected a sea-breeze. On Passageweather GFS and COAMPS charts for the area were completely different.

 

[philiphurst]

I remember entering the Blackwater a couple of years ago in light-ish airs. When looking at the Bradwell wind-farm, approximatley half of the turbines were turning clockwise and the rest anti-clockwise. Pretty sure that's not normal.

 

[maby]

I remember entering the Blackwater a couple of years ago in light-ish airs. When looking at the Bradwell wind-farm, approximatley half of the turbines were turning clockwise and the rest anti-clockwise. Pretty sure that's not normal.

well, the blades on those turbines feather, so I guess that they can be configured to rotate in either direction. Is there any engineering case for alternating the direction over time to even out wear?

 

[AntarcticPilot]

I think the SE breeze set in quite early in the day, before one would have expected a sea-breeze. On Passageweather GFS and COAMPS charts for the area were completely different.

I was thinking of something I saw over a road in the Fens once - the hot road, despite being very narrow, was causing an updraft over the road which was clearly visible. So a narrow linear feature with a difference in temperature can cause local effects on even the smallest of scales.

 

[rich]

Hi all, I will be up your way next week, I’m spending the summer with my mate on his cat Brigand, will be going south, give us a wave when you see us.

 

[franksingleton]

Without knowing any other information, the sea breeze explanation is one possible answer. In Reeds Weather Handbook, I give some examples such as across Torbay, between Berry Head and Thatcher Rock. Also either side Plymouth between Yealm Head and Rame Head. Another possibility is similar to the Cowes effect where a southerly divides partly because of topography and partly a sea breeze effect. The two boat spinnakering in opposite directions is well known in all these.

Such effects are well below what any GRIB output will show you. Global models such as the GFS, ICON, ECMWF grid lengths are far too long. COAMPS with a 4km grid will probably not cope either. A really good detailed model such as the Met Office or Meteo France 1.3 km grid models might give a clue. Commercially run detailed models are unlikely to do so either simply because they do not have any detailed weather input.