In message . com,
Graham Easterling writes

http://tinyurl.com/ocmmr

This is the week I'm due to be in St Ives on holiday...

I saw that, I think some perspective is needed.

In Newquay (the nearest I've got full tide details to St Ives), the
highest Spring Tide in September (9th) is 7.8m above chart datum, which
is about as high as it gets.

There were 7.9's on 25th & 26th Sep 1980. (I knew I'd eventually find a
reason for keeping old tide tables).

However the 7.7m in October is achieved at
some point most years.

Yes, I kept the list of tides for that week you posted back in January.


The exceptional September tide is just 4-5"
above the normal highest tide of the year.

There seems to a 4 year cycle - over that period, the biggest annual
tide varies between about 7.5 & 7.8m.

In fact there seem to be all kinds of cycles involved in calculating
tides - whether the biggest are with new or full moons, time of year,
etc. I wonder if there's a good website which lists most, or all of the
(non-random) influences on tide height?

If low barometric pressure is combined with an onshore gale it can
raise the astronomical tide by a few feet. Add to this a 10'+ swell,
not uncommon in Cornwall, then a Spring tide a few inches above the
normal for the equinoctal period is actually of fairly minor
importance. Adverse weather conditions on a large spring tide are bad
news, whether the tide is 7.6m or 7.8m.

Well, the place I'm staying is on the Wharf, about 150 yards from
Smeaton's Pier - fortunately it's on the first floor though, and the
entrance is about 10 feet higher than the sea wall...

Gonna make sure my camcorder batteries are fully charged, though!

During the October 2004 storm which hit Penzance, the swell was 15-20',
the storm surge several feet, so huge waves were breaking right on the
sea defences. It was truly scary to watch. At Mousehole the sea was
breaking up and washing away concrete normally 10' above the normal HW
Spring Tide level. It was flooding cottages around the harbour by
shooting up into the air, and going down the chimneys. So a Spring tide
a few inches above the normal equinoctal spring, is really that big a
deal. But it's certainly something to watch.

I've noticed that the high tide starts reaching the road above the
slipway near the Sloop, once the predicted height is around 6.8m (in
normal weather).
--
Paul Hyett, Cheltenham (change 'invalid83261' to 'blueyonder' to email me)