"Super Tides" is there anything in this?

All that'll take is a quick glance at the Reeds Tidal coefficients page.... I'm sure someone with access to one will be here forthwith.
 
Those 'super tides' (we call them king tides here) occur at every equinox -- I don't think there's anything special about this year. The thing is that when they occur there are quite likely to be low-pressure systems around, and the effects of a spring tide combined with low pressure and perhaps a build-up of adverse winds are both very enhanced and very observable.

The water level here was about 4' higher than a normal high tide, which was sufficient to cover all the saltings and about 150' of grassed area to reach this house. This was an equinoctial tide on the upper reaches of an estuary, with high rainfall producing strong levels of incoming water flows, combined with both low pressure (producing storm surge) and adverse winds blocking the ebb --

record-high-13s.jpg
Mike
 
Wooden Boat Fittings said:
Those 'super tides' (we call them king tides here) occur at every equinox -- I don't think there's anything special about this year.
Click to expand...

The whole discussion is around whether they ARE bigger this year. The data on the POL website is pointing towards that being the case. Even at the equinox, the springs are usually well short of HAT, but I gave an example above where the highest spring is predicted to be exactly the same as HAT this year.
 
The tidal coefficient on 21 March is 119. So, yes, very big.

Mean springs is 95, whereas 120 is a "very big spring tide". Not sure, though, whether 120 is exactly equal to HAT or whether (astronomically speaking) you can get a coefficient greater than 120.

Big spring tides again at the end of August/beginning of September and again at the end of September.

Edit: The tidal range at St Malo on 21 March is 13.25m. You're gonna need a longer anchor warp. :eek:

2nd edit: No mention of tidal coefficients in the English version of the Wikipedia entry on tides, but no surprise since it is more commonly used by the French. The French version of Wikipedia does, however, describe a 120 coefficient as:

la plus forte marée possible
Click to expand...

i.e. the biggest (tidal range) possible.
 
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I saw somewhere that this year is the peak of an eighteen year cycle of the moons orbit coming closest to earth thereby giving us three 'super tides' this year. I believe we have just had one of them.
 
Last Thursday was 4.25m at Harwich, however looking through the tide tables for the year there are 6 more to come that are higher including 4.35m in September.
 
How high were the tides at the end of August 1992? Are the coming highs likely to rival this scene of unusual inundation at Bosham in West Sussex?

 
dancrane said:
How high were the tides at the end of August 1992? Are the coming highs likely to rival this scene of unusual inundation at Bosham in West Sussex?

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Takes more than a tidal prediction, with factors like low atmospheric pressure and wind driven storm surges.

I must say last winter's high water at Langstone village ( the houses have washboards on the front doors for good reason ) was the highest I've seen but I think it's a cyclic thing like stronger winds than in our youth, with a bit of luck we're through the worst now.
 
Last spring we had tides on the Solway which were two metres higher than usual. Somewhere I have a video of a Drascombe which had floated off its trailer at the Solway Yacht Club boat park, and there was a bilge keeler lifting delicately out of her cradle with each ripple.
 
I looked at St. Peter Port over period 2010 -2015 and 2015 seemed to be same as 2010. So might be journalistic exaggeration to call them "Super-tides" and indicate that 2015 is very special.

Date_______Low___High___Range
21-Mar-15___0.1___10.3___10.2
02-Mar-14___0.2___10.2___10.0
12-Feb-13___0.5___ 9.9____ 9.4
09-Apr-12___0.4___10.0____ 9.6
21-Mar-11___0.1___10.2___10.1
02-Mar-10___0.1___10.3___10.2

It might be an 18 year cycle as suggested but I imagine that most of the major variable factors (relative distances and positions of the sun, moon and Earth) change most in a much shorter cycle. I suspect that longer cycles may only modify maximum tides by a fairly small margin.

2015 doesn't appear to be any worse than 2010, based on a quick look at one port.

Perhaps it's the frequency of higher than usual tides? If there are more 10.1m high tides in a given year then the risk of flooding will be higher as combination of adverse weather and a very high tide becomes more likely.

EDIT: Just looked at the article again "There are expected to be about six periods of so-called supertides". I think that's the answer, not the absolute maximum but the frequency of tides approaching this maximum.

I already knew we'd get highest tides around March/September and so just looked a worst cases in those months. So missed seeing the real problem for a little while.
 
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The Telegraph in that article show flooding in Welshpool at 72m above sea level , so that would be very bad!!!!!!!

Guernsey tides a little higher at 10.3m not an issue unless very high winds as well at the time of high water.

The media love weather, it could, will it wont it, my god its bad( pictures of small waves with a telephoto) then a later programme about the "disaster"!

Having seen recent " weather bombs" ie a bit windy for a while, now Telegraph today forecasting a "Tidal wave of snow " for north America, they have slow news days and have run out of superlatives.

Get some meaningful statistics and Get a grip!
 
doris said:
I saw somewhere that this year is the peak of an eighteen year cycle of the moons orbit coming closest to earth thereby giving us three 'super tides' this year. I believe we have just had one of them.
Click to expand...

I'm not sure of the periodicity, but yes, last year saw the moon coming closer to earth than normal. There were supposed to be three 'super moons' when (they said) you could tell it looked slightly bigger because it was closer.

You would think that this might have some effect on tidal height, but --

Seajet said:
Takes more than a tidal prediction, with factors like low atmospheric pressure and wind driven storm surges.
Click to expand...

... I think any effect will be swamped for these reasons.

Mike
 
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