Explosive Cyclogenesis ... ... and the joys of really big storms.
By Tony Butt
[This article first appeared in The Surfer's Path in 1999. We thought, with a 928mb low about to turn the North Atlantic into a maelstrom of memorable proportions, this aint a bad time to brush up on our explosive cyclogenesis, and some of the biggest storms in North Atlantic history]
The weather forecast is showing a huge low just west of Ireland. Its about to deepen even further, and swing east over the UK. Its isobars are so close they’re almost touching. The centre looks like a solid black mass. The weather manis warning of impending doom. Lives will be endangered, there’ll be heavy financial repercussions, insurance claims and a strong chance that many people’s worlds will fall disastrously apart. Meanwhile, you’re stoked. The storm is out there, and the swell is inevitable. It’s like you just won the lottery and all you have to do is wait for the money to come in. You start planning with glee - what board, which spots, which days and times will be best…. To many surfers this is a big part of surfing. If you’ve been doing it for a number of years, the biggest, meanest storms that appear on the weather chart will end up sticking in your memory. Some of them may never have produced rideable surf for you, but nonetheless, they’re a source of fascination. This article is about some of the deepest lows that have existed in the North Atlantic, and some of the most disastrous storms that have ravaged the UK, from where I write. These storms are well documented in the meteorological literature, and they have often been given names (like hurricanes), just to add to that air of human-like unpredictability.
The Fastnet Storm, August 13th 1979
A flotilla of yachts set sail from Cowes, Isle of Wight. They were supposed to race to Fastnet Rock, and then back to Plymouth. Of the 303 that set out, only 85 made it. Fifteen lives were lost and 136 people had to be rescued by helicopter. This well-known disaster, the Fastnet Storm, was caused by winds of over 80mph, whipped up by an unexpected low pressure system which developed over Ireland. It wasn’t actually that deep, (about 980mb), but the fact that all those boats got caught out, makes it a real tragedy. One interesting thing about the Fastnet Storm is that with all those boats stuck right in the middle of a large mid-latitude depression, each one carrying a barometer and an anemometer, a very comprehensive study of what goes on inside one of these lows was able to be made. Also, the reports of some of the surviving crews were valuable to meteorologists, like descriptions from the crew of ‘The Gremalkin’, talking of waves “like blocks of flats…”
The stricken boat Gremalkin after a night of 30-60ft seas in the Fastnet Race, January, 1979
The Great Storm of 15-16 October 1987
This was
the one where Michael Fish, the weatherman got ripped to shreds by
the media for not predicting it the day before. The Sun newspaper
even called for the resignation of Professor J. T. Houghton,
Director-General of the Met. Office. Personally I don’t know what
the fuss was about. I clearly remember the weatherman saying “…it
will be very breezy in the Channel…”
This storm didn’t produce much in the way of surf because it
deepened to about 956mb when it was already over the land. However,
it did cause considerable damage to the heavily populated south of
England. With gusts of over 115mph, eighteen people lost their
lives, and an estimated 25 million people (and 15 million trees)
were affected in one way or another.
There is an endless list of incidents connected with this storm. For
example, at Porthleven, three people had to be rescued when their
own rescue helicopter ditched into the sea, and at Harwich a prison
ship containing 50 inmates broke free from its moorings and drifted
around for two hours. And minutes before a tree smashed down his
house, Dr. H. Lawes of Noble Denton Weather Services reports, “…I
telephoned the forecast office… the synoptic situation sounded
interesting from an academic point of view, but following another
loud crash I put the telephone down rather hurriedly”.
Again, the Burns Day Storm of 25 January, 1990 got to its deepest
after it had settled over Northern England, but it did generate
enormous swell earlier on, as it deepened just west of Ireland. Most
recognised breaks north of Southern Portugal were out of control,
although spots south of there were going off. On the land, it was a
similar story to the Great Storm of ‘87. Millions of trees got blown
down, 47 people lost their lives, and hundreds of millions of pounds
worth of damage was caused.
Brear Storm 1993 was predicted to drop to 909mb but in the end it only reach 914mb. Only.
The Lowest Lows
Sometimes, all the factors to do with the jet stream, the sea surface temperature, the polar ice, the butterfly flapping its wings 10000 miles away etc., all coincide to produce a depression which gets incredibly low. Usually these lows suddenly deepen, as if they were always ready to be triggered off. In the world of meteorology, if a low deepens more than 24mb in 24 hours it’s called “explosive cyclogenesis”. The two lowest barometric readings recorded in this part of the Atlantic have occurred in the eighties and nineties. The first was the Atlantic Cyclone of 15 December 1986, which got down to 916mb, and the other one was the Braer Storm of 10 January 1993. The Braer Storm has been much better documented. It took its name from the final destruction of the Braer, a large, loaded oil tanker which had become stranded on rocks off the Shetland Islands by another storm a week earlier. Dipping to 914mb, it has been acknowledged to be the deepest Atlantic mid-latitude depression ever recorded. The experts thought it was going to deepen even more. I can remember vividly listening to the Shipping Forecast from a crackling old radio whilst huddled in the back of a van at Mundaka: “Rapidly deepening Atlantic low, expected just west of Bailey, 909mb”, and the wind for Bailey was “… Force twelve or more…” which is also quite rare. Needless to say we were expecting some surf.
What Sort of Surf do These Storms Bring?
Not necessarily that good. It depends on so many other factors, like the fetch length, how long the storm stayed in one place, the direction of the fetch, etc. The Braer Storm produced some great surf, but not really as big as many had expected. The low didn’t persist long enough, despite a very tight, intense centre similar to (but not the same as) a hurricane. On the other hand, the Cyclone of ‘86 probably produced some all-time surf throughout the whole Atlantic. I was in Morocco at the time, and I remember some local rolling up with a newspaper on a rickety old bike; “Hey meester, beeg waves for joo, no feeshing for us”. Even he could see there was something unusual about today’s weather chart. It took six days for that swell to arrive, but when it did, it was 10ft and super-clean. Anyway, the general consensus is, these storms definitely produce big waves, and the more of them there are, the more often we’ll get big surf in the Atlantic.
Hmm … Morocco. Not a bad place to be in the next few days. Photo: Ricardo Borghi
So Is the North Atlantic Getting Stormier?
Well, yes, so it seems. And not only that, but the thing that
affects us directly, namely wave heights, have been shown to
increase significantly over the last few decades. Measurements from
wave buoys and weather ships have shown that, in 1960, the maximum
wave height in the Atlantic was about 12m. There has been a
systematic increase, and now, in the late nineties, the average
maximum height is around 18m. Long-term trends in wave heights are
intimately linked with how stormy the ocean is, so we can safely say
that the Atlantic has got quite a bit stormier since the early
’60s. Whether this trend will continue is anybody’s guess. It’s
probably just the upward side of a much longer-term oscillatory
pattern (like El Nino, but over many decades). We haven’t got good
enough meteorological records for that – we don’t really know.
For people like myself, who strive to try and
predict these types of things, it’s tough, even as our forecast models get better and better. On one hand we have
to fool ourselves, and those who pay us, that one day we might be able to
predict everything (otherwise we’d give up altogether). On the other
hand, we must keep in mind that forecasting is inexact. The fundamental laws of quantum mechanics forbid us from
making perfect predictions of anything, let alone the weather.
Which
is a really good thing, because otherwise both surfing and science
would be forever predictable, and not worth a whistle in the wind.
Tony Butt is author of The Surfer’s Guide to Waves, Coasts and Climates, published by Alison Hodge. If you want a copy, you can get one free right now by joining Surfers Against Sewage, here.
This article first appeared in The Surfer’s Path way back in 1999.
