pvb
Well-Known Member
The surge is slightly negative at the moment - see http://www.ntslf.org/storm-surges/latest-surge-forecast?port=Felixstowe
Possible Storm Surge Tuesday
- Thread starter Habebty
- Start date
The surge is slightly negative at the moment - see http://www.ntslf.org/storm-surges/latest-surge-forecast?port=Felixstowe
Lucky Duck
Well-Known Member
Does anybody remember what the situation was like at Suffolk Yacht Harbour last time around?
sailorman
Well-Known Member
within 150m/m of the pile tops i was told
pvb
Well-Known Member
Was that 10 Oct last year? If so, and if tonight's is 300mm higher....
Phoenix of Hamble
Well-Known Member
Cantata, the surge is forecast to be starting about now, and steadily building through to about 5am tomorrow morning at its peak
Hydrozoan
Well-Known Member
That's the ODN to CD correction for Felixstowe (see http://www.ntslf.org/tides/datum). Adding it to the Environment Agency's 2.8m forecast would give 4.75m for the predicted tide level, against ca. 5.30m obtained by adding the predicted storm surge for Felixstowe (http://www.ntslf.org/storm-surges/latest-surge-forecast?port=Felixstowe) to the tidal prediction for Harwich (relative to CD). That's a difference of ca. 0.55m.
CD Harwich is 2.02m below ODN (http://www.hha.co.uk/proxy.asp?proxy_url=library/files/7806ded0-6bbc-4291-881a-e69bffc599f7.pdf) so the Harwich-Felixstowe CD difference is 0.07m. The NTSLF forecast surge height at HW is ca. 1.0m, and the Environment Agency's 0.91m, which is ~0.1m difference.
So whence comes the other 0.3m or so - or have I got it wrong, or am missing something?
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sailorman
Well-Known Member
the last surge was 05/12/13
The CG told me he was expecting the HW of 4.1 + 2m when i phoned him at approx 17.00
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pvb
Well-Known Member
-0.09m, surely?
Hydrozoan
Well-Known Member
Indeed, my apologies - I was just correcting it as you posted.
But it doesn't alter the fact that I can account for less than 0.2m difference from the CD and surge prediction differences, against the 0.55m difference in predicted HWs, so I remain puzzled.
pvb
Well-Known Member
Ah, OK, so December's high was around 6.1m, and tonight's is forecast around 4.75m, so shouldn't be dramatic.
sailorman
Well-Known Member
it now looks like the LW is being held back from ebbing as prediction
http://www.ntslf.org/data/realtime?port=Harwich
http://www.ntslf.org/data/realtime?port=Harwich
Phoenix of Hamble
Well-Known Member
also looking at the current Harwich measurements (assuming they're accurate), its looking worryingly like the surge is a bit bigger than they forecast already... extrapolating the current graph by eye alone, it looks like a total LW of about 1.3m, versus a forecast from dennjc's calculations of about 0.8. If that difference continues, then both Shotley and SYH are very very close to trouble.Sad man that I am.....
I made myself a graph of what to expect
Because it does not coincide with HW at Harwich - I believe our boats to be safe this time
But - had it coincided then it would be worse than last time
EDIT: latest measurement looks a bit less frightening...
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sailorman
Well-Known Member
i was o/b from around 17.00 on that day & decided to go out on the river rather than risk the dodgy piles in the marina. that pile broke 2 months ago & 2 new longer ones have replaced it. "A" pontoon pile is leaning over though & with a strong NW wind could be an issue
wingdiver
Well-Known Member
Actually NW is beam on to the hammerhead (and us) which means that the pontoons are pushing along their length towards shore and the force is being shared by the other pile on A and the new ones on the pontoon along the shore.
Far worse would be SW or NE when the 'loose' pile would be subject to the most sideways force from the pontoons.
(he says with fingers crossed)Also, on the day of the big surge in Dec 2013, the issue wasn't dodgy piles but ones that were too short to retain the pontoons on when the water level rose. This was sorted by welding on an extra metre of pile on all the old ones.
I hear all the old piles on A, B and C are to be replaced soon with an additional one on the hammerhead on A
cool
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sailorman
Well-Known Member
No doubt their on the caseActually NW is beam on to the hammerhead (and us) which means that the pontoons are pushing along their length towards shore and the force is being shared by the other pile on A and the new ones on the pontoon along the shore.
Far worse would be SW or NE when the 'loose' pile would be subject to the most sideways force from the pontoons.
then the gate tomorrow
wingdiver
Well-Known Member
No doubt their on the case
then the gate tomorrow
Hope the lock isn't the usual quality. Perhaps one like on the heads......?
sailorman
Well-Known Member
Yes that very good, shame they have stopped the "beeps" as one isnt sure if its actually working, i do know the 2 D lamp over head has been us for 6 monthsHope the lock isn't the usual quality. Perhaps one like on the heads......?
pvb
Well-Known Member
From what I can gather, the high water level at Harwich on 5 December last year was 3.45mAODN, so tonight's predicted 2.8mAODN shouldn't be a major problem.
sailorman
Well-Known Member
the problem on 05/12 was the very high LW. The LW @ Fox`s was like a normal 1/2 tide in the lift dock
dennyjc
Well-Known Member
Here's all the data from December 05th 2013 for comparison
Because of the timing of the surge
This time the water will ultimately reach a slightly lower high mark
....still plenty scary. Especially for those marinas that have not yet done the remedial work
There - I told you I was a sad man
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