From Malin Head to Mizen Head E-Book

Joanna Donnelly

• Herausgeber: Gill Books
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2023

Seitenzahl: 249

Beschreibung

Broadcast at 6 a.m. and midnight on RTÉ Radio 1, the Sea Area Forecast has come to occupy an almost sacrosanct place in the day for many. Its familiar (though often incomprehensible) language acts as a wake-up alarm for a proportion of the population and sends another swathe of them to bed at the end of the day. Yet few people truly understand its unique language and the significance of the romantic sounding headlands whose locations are central to revealing the incoming weather. From Mizen Head to Malin, Valentia to Loop Head, Carlingford Lough to Hook Head, rising or falling slowly, backing south-east to north-east or veering south-to-south-west – what does it all mean? Here, meteorologist Joanna Donnelly goes on a journey around Ireland's Sea Area Forecast. Visiting the places that are a familiar part of the daily broadcast and explaining the history, language and science associated with it, From Malin Head to Mizen Head fans our endless fascination with the weather while sweeping us away on a journey around Ireland's most remote headlands.

Leseprobe

This book is dedicated to the memory of my mother, Marie Kelly.

Her sudden departure from this world set me adrift. This journey around the headlands has helped me to start to right the course.

contents

Cover

Title page

Dedication

Introduction

Chapter One

From Loop Head to Slyne Head to Erris Head

Chapter Two

From Bloody Foreland to Malin Head to Fair Head

Chapter Three

From Belfast Lough to Carlingford Lough to Howth Head

Chapter Four

From Wicklow Head to Carnsore Point to Hook Head

Chapter Five

From Roches Point to Mizen Head to Valentia

Epilogue

Acknowledgements

Copyright

About the Author

About Gill Books

introduction

I’m often asked – in fact, it’s a guaranteed question – what, for me, is the favourite part of my job.

People grow up with the weather forecast. It’s on in their houses because grown-ups want to watch the news. The weather forecast comes on after the news and it’s something that kids are okay with. It’s the same every day – basically. Yes, the weather is different, but the presence of a presenter standing in front of the blue screen is the same. No deaths, births or marriages, a fixed length and format. It’s nice and reassuring, and kids like that.

So, kids grow up and they see these guys presenting the weather and they think, that’s a weather forecaster. Some think they’d like to be a weather forecaster, some even think they could be a weather forecaster.

I was not one of those people. I was only interested in maths or science and absolutely not in weather. Don’t get me wrong, I’ve always loved a good thunderstorm, but I live in Ireland, and we don’t get good thunderstorms here. I’ve seen more thunderstorms in an afternoon on the continent than I have in my lifetime in Ireland. I also like mist. I love autumn because it’s a fairly misty time of year around these parts. But on the whole, I’m not all that interested in the weather.

What I am interested in, however, is what makes the weather. Not in the sun and the rotation of the Earth and uneven heating, but in the physics and the laws and the variables. I love the maths here, and as I always say, maths is the language that science speaks. As I’ve progressed through my career over the past 27 years, I’ve also learned that I love to communicate all of this to the public. What makes weather work is something that many other people are interested in too.

So, my favourite part of the job is not and never has been standing in front of a blue screen pointing at where the clouds should be. My favourite part of the job is the science and the communication of it in the most effective way possible so that people can understand it – specifically, the sea area forecast.

WHAT IS THE SEA AREA FORECAST?

The sea area forecast is a part of the weather forecast, the primary focus of which is ‘the protection of life and property on the island and our waters’.

These days the forecast output is sent directly from the computer models to the handheld devices of almost every adult member of the population. There are forecasts on social media, TV, print media, radio and the internet. It’s in any format you can come up with and it’s updated several times a day. There are weather enthusiasts taking every chart produced by models from around the world and commenting on them on internet chat rooms, sometimes fixating on snow and sometimes on high temperatures, and often of the opinion that they know better than the professionals. And sometimes they do.

But the sea area forecast is different. It is sacred ground. Although it’s now available online as well as on the radio, it really hasn’t changed since I started in Met Éireann, Ireland’s national meteorological service, in 1995.

Starting at 0600, it’s updated every six hours. Irish coast radio stations make a prior announcement of weather forecasts on Marine VHF Radio Channel 16 and then broadcast the forecast on the named relevant VHF Radio working channel.

It’s broadcast by RTÉ Radio 1 just after 6 a.m., immediately after the news headlines, and again just before the pips for midnight. As a result, it has come to occupy an almost sacrosanct place in the day for many, its familiar, unique (and often incomprehensible) language acting as a wake-up alarm for an astonishingly high proportion of the population and sending another swathe of them to bed at the end of the day.

We, the weather forecasters at Met Éireann, work 24 hours a day, 7 days a week, 365 days a year. It’s not the same person all the time – we have a roster and there are various jobs to be done. There are the TV broadcasts done from a sub-office within RTÉ. There’s a shift that deals with daily requests from the commercial sphere, from racecourses to golf courses, pigeon fanciers to builders and movie makers. We have aviation forecasters who deal with the skies over the country and then we have the ‘main desk’ – the ‘chief’ or ‘duty’ forecaster. We’ve been switching and changing the name for as long as I’ve worked there and I don’t think we’ve managed to agree on one yet. I’m partial to ‘duty forecaster’ myself.

The duty forecaster is responsible for updating the national forecast that goes out on the website and radio, they’re responsible for the warnings issued on their shift, and they’re responsible for the sea area forecast.

The job I do entails certain steps, and we’ll talk about those steps in more detail as we go through the book. For now, let’s just say that once you’ve put in the work you produce a picture of what you think the future is going to look like. There is a huge amount of uncertainty. Later we’ll get to why there’s even more uncertainty here on this island than there is in just about any other place on the planet, which means that sometimes it can go wrong.

I hate it when it goes wrong. And I do mean to use the word ‘hate’. But I still understand that it can go wrong and I live with that. That’s part of the job. An area of low pressure not caught correctly by the models, overestimating rain or underestimating cloud – these things happen and there’s no point in getting bent out of shape about it. What we can do is apply due diligence in the processes of the job, meaning we’ve looked at every field, digested every variable, applied all our knowledge and experience, and produced the best product we can.

The sea area forecast takes six hours to prepare. There are six hours between updates, and for those six hours, the role of the forecaster is to assess the information available and update the forecast as necessary. Typing the forecast takes about 10 minutes, unless you’re only using one finger and can’t remember where the tab button is (or what it is for) – we’ve had those forecasters too.

I’ve heard it said that in order to build an apple pie from scratch you must first create the universe, and that’s valid here. If I am to tell you how to make a sea area forecast I must first tell you how it all works. So in the next few pages, I’d like to tell you a little bit about why we forecast for the sea – which, as it turns out, is why we forecast at all. After all, the sea area forecast came first and it’s still first now.

A LITTLE BIT OF HISTORY

The Royal Charter Storm

In August 1859 a passenger ship carrying around 450 passengers and crew set sail from Melbourne. Its final destination was the docks at Merseyside in Liverpool.

Australia was booming, and the gold rush that had started in 1851 was still drawing speculators from around the world. Energised young men, drawn by the promise of riches beyond their hopes in Europe, set off to make their fortune and take it back home. On this return journey, the ship was laden with gold and held a vast amount of wealth.

A relatively new type of ship, it was a massive 2719-ton iron-hulled steam clipper. Prior to the proliferation of steamships, global trade was limited to the times of year when it was possible to travel by sail. Doldrums, storms and monsoons meant the weather dictated when trade could take place.

Once steamships came into the picture, global trade could go on undisturbed all year round, with the steamers ploughing through wind and rain. The Royal Charter was a fast ship and was able to make the journey from Liverpool to Australia via Cape Horn in around 60 days. There were first-class cabins and plenty of room on board for passengers and crew to enjoy a relatively comfortable experience.

After a journey of more than 20,000km, with just 70 more to go to its home port, the ship met a storm just off the coast of Anglesey – the Royal Charter Storm.

On the night of 25 October, the on-board barometer started to drop dramatically as pressure fell with the advancing storm. As they passed the tip of Anglesey, they tried to pick up the pilot who would take the ship the final few kilometres to port, but the sea was too rough and the pilot was overpowered. Winds of storm force 10 on the Beaufort scale were recorded, soon rising through a violent storm to reach hurricane force 12.

It must have been terrifying for the men, women and children on board the ship, with their huge vessel tossed like a bean on waves that would have been crashing like thunder overhead as they huddled together in their staterooms and cabins.

Within sight of land, the ship was anchored and the crew cut their masts, but first one and then another anchor chain snapped, and the steam engines working at their capacity were no match for the gale force northeast wind. The ship was beached and then broken to pieces on the rocks with the rising tide.

With land so close by, many tried to swim, but in the turbulent seas and weighed down by their clothes and possessions, most didn’t make it. Many were killed when they were bashed against the rocks and drowned. Joseph Rogers (a member of the crew, born Guzi Ruggier and originally from Malta) swam to shore with a rope and managed to rescue several people, earning him recognition from the townspeople of nearby Moelfre. Charles Dickens travelled from London to Moelfre to report on the tragedy that had claimed 459 souls. Twenty-one passengers and eighteen crew members were rescued or made it safely to shore. None of those saved were women or children.

The storm was named for the ship but went on to take more lives around the coasts of the UK that night and the next. In total more than 800 people lost their lives on the sea and land, with 133 ships sunk. In just one storm, this was twice as many as the total number who had died at sea around Britain and Ireland in the previous year.

There was also a financial loss. The ship was insured for more than £300,000, but it was estimated that the value of the gold lost was considerably more than that, in just one ship.

The first weather forecasts

Following the Royal Charter Storm, Vice-Admiral Robert FitzRoy began the first gale warning system. When a gale was expected, a network of warning cones would be hoisted at ports as a warning for those about to head to sea.

Vice-Admiral FitzRoy had been made head of what would later become the British Met Office in 1854. In the year following the 1859 storm, he distributed barometers, many of which he designed himself, to a network of 15 coastal stations around Britain and Ireland, including Valentia and Malin Head, which are still used today. He then had the readings sent to him in London, where he produced what he first termed a ‘weather forecast’. These forecasts were published in The Times from 1861.

His warnings and forecasts went far beyond any that were available at the time and were at the forefront of the science of the day. Queen Victoria herself requested a personal forecast from Vice-Admiral FitzRoy for a crossing she was planning to make to the Isle of Wight. I bet he was up half the night worrying about how it went; just as I was when my friends asked me whether they should book a bouncy castle for their children’s birthday party or when the film director and producer John Carney asked me if he needed a marquee for his wedding day!

Since then, the technology used to forecast gales and produce warnings has evolved, and the method of communicating the warnings has become more sophisticated, but the basic principle remains the same: we check the readings; we forecast a gale; we communicate it to the ships.

A gale warning is issued when winds are expected to reach gale force 8 or above. But there are many more hazards at sea besides the wind, and so the sea area forecast grew from the gale warnings. Now it provides an update on the wind, the weather and the visibility expected at sea.

The sea area forecast follows the same format at all times, designed so that even if all else fails and technology is lost, a ship at sea with a functioning radio should be able to use the information in a sea area forecast to navigate safely through or around bad weather to a safe port. It is this fixed format that has enabled it to occupy such a special place in our imaginations. Its rhythmic quality is both comforting and reassuring. The first part of the forecast tells if there are operational warnings in place, and in addition to the gale warning we issue what is called a ‘small craft warning’.

While the gale warning covers the seas out to 30 miles off the coast of Ireland, the small craft warning extends to 10 miles off the coast and is designed for the smaller leisure or pleasure boats that are found nearer land.

Miles and knots

Although Met Éireann uses the metric system in forecasting, nautical miles and knots are used at sea. A knot (kt) is one nautical mile per hour. The nautical mile is used to measure distance over the sea and is just a little longer than the miles we’re used to on land – a nautical mile is measured as one minute of latitude and is approximately 1.15 miles. To quote the great Joe Pesci in the movie Lethal Weapon – ‘Put them around boats and water and all of a sudden everything becomes nautical.’ I’m paraphrasing of course – this is a family-friendly book and Leo Getz had a foul mouth.

The meteorological situation

Now we’re getting to the guts of any forecast. Every day in the office the duty shift changes three times. At each changeover the duty forecaster hands over to their relief with a briefing. Every good briefing should begin with ‘the meteorological situation’, and every good forecaster should, having been given a good meteorological situation, be able to construct the rudimentary forecast for the next day, just like Vice-Admiral FitzRoy. That’s basically what he was doing, after all.

While I don’t want to get bogged down in the physics, there’s hardly any point in going on if my reader – that’s you – doesn’t have the most basic grasp of this topic. As we move through the chapters of the book, I’ll describe various aspects of meteorology in a little more detail, but for now, we’ll manage with the basics.

Weather is defined by the movement of air, and air moves from areas of high pressure to areas of low pressure. In areas of low pressure, the air is rising and water vapour is condensing in the cooling atmosphere, forming clouds, which sometimes bring rain. In areas of high pressure, the air is descending, fizzling out the clouds and clearing off the skies. Areas of high pressure, also known as anticyclones, are associated with fair weather and light winds.

Areas of low pressure have lots more names – depressions, storms, cyclones, hurricanes and typhoons. Rising air circulates around a centre where the air is still – in a hurricane this is the eye and a hurricane, called a typhoon in the southern hemisphere, is a non-frontal area of low pressure, has a unique construction, and, of course, can be devastatingly destructive. We’ll look more closely at storms and hurricanes later in the book.

A storm is a depression in which there are winds of force 10 or higher on the Beaufort scale, and a cyclone is the same thing as a depression. A tropical cyclone is a circulating low-pressure system that forms over warm ocean waters. (This is where some people start to mix things up. We don’t mean to deliberately confuse people, but it does get a little complicated at times, and multiple names for the same or similar things don’t help.)

When conditions are right, these develop further into hurricanes, with wind speeds of Beaufort force 12 or higher, and just to annoy people further, hurricanes are called typhoons over the Pacific Ocean. However, low pressure is low pressure, and whatever we call it the same thing is happening – in the northern hemisphere, air moves anticlockwise around the centre of the low, while in the southern hemisphere, this is reversed. And air correspondingly moves clockwise around an anticyclone.

Yes, I see the confusion. And no, I don’t know why they called anticyclones ‘anticyclones’ when the air is moving clockwise and cyclones have the air moving anticlockwise. It’s just another thing really smart people did to annoy the general public. They like to have their fun.

But really, there are simple rules that will help the budding meteorologist to navigate their way around the weather, no pun intended. Buys Ballot’s law is the easiest in my opinion: if you stand with your back to the wind in the northern hemisphere, then low pressure is on your left. Add this to the other rule above – that air moves from areas of high pressure to areas of low pressure – and we have the start of figuring out where the weather is coming from and going to.

THE BEAUFORT SCALE ON LAND AND AT SEA

Beaufort

Mean wind (knots)

Wind descriptor

Sea descriptor

Land descriptor

0

<1

Calm

Calm (glassy)

Smoke rises vertically

1

1–3

Light air

Calm (rippled)

Direction shown by smoke but not by a wind vane

2

4–6

Light breeze

Smooth (wavelets)

Wind felt on face, leaves rustle, direction shown on wind vane

3

7–10

Gentle breeze

Slight (wave height 0.5–1.25m)

Leaves and small twigs in constant motion; light flags extended

4

11–16

Moderate breeze

Slight – Moderate (wave height 0.5–2.5m)

Raises dust and loose paper; small branches moved

5

17–21

Fresh breeze

Moderate (wave height 1.25–2.5m)

Small trees in leaf begin to sway; crested wavelets form on inland waters

6

22–27

Strong breeze

Rough (wave height 2.5–4.0m)

Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty

7

28–33

Near gale

Rough – Very rough (wave height 2.5–6.0m)

Whole trees in motion; inconvenience felt when walking against the wind

8

34–40

Gale

Very rough – High (wave height 4.0–6.0m)

Twigs break off trees; progress generally impeded

9

41–47

Strong gale 3

High (wave height 6.0–9.0m)

Slight structural damage (chimney pots and slates removed)

10

48–55

Storm

Very high (wave height 9.0–14.0m)

Seldom experienced inland; trees uprooted; considerable structural damage

11

56–63

Violent storm

Very high (wave height 9.0–14.0m) damage

Very rarely experienced; accompanied by widespread

So we start the sea area forecast stating exactly where the areas of high pressure and low pressure are around Ireland. This is the meteorological situation.

With depressions, we state the lowest atmospheric pressure and try to give as close an approximation to its location as possible – for example: ‘A depression of 998hPa has its centre approximately 50 nautical miles northwest of Malin Head.’

Anticyclones are larger and slower moving, and we tend to state their highest atmospheric pressure with an indication of the geographic area that can best identify the location – for example: ‘An anticyclone with a centre of 1024hPa has its centre over the North Sea.’

The scientific community understands a standard atmosphere to be 1013hPa (hectopascals). This is the number agreed to be the mean for the purposes of mathematical calculations, but high pressure and low pressure in meteorological terms are determined by the flow of air around the centre and not by the value in hectopascals. So we can see anticyclonic conditions with a centre of 1009hPa, for example, and we can have a depression with a central pressure of 1015hPa. It’s the movement of air that’s the defining characteristic, not the number.

Once a sailor at sea has the positions of the highs and lows, they should be able to start to figure out if they are going to face bad weather on their route. In brief, anticyclonic conditions generally mean fair weather, although there are caveats (there are always caveats). Anticyclonic conditions can also mean fog and slack or no wind, and these are no friend to anyone travelling by means of sail.

Now we move to the body of the forecast, and this is where we divide the area into blocks so that we can paint a picture of the weather as it is at the moment and how we expect it to change over the period of validity of the forecast. The forecast validity period is 24 hours, with an outlook for a further 24.

The headlands most used, going clockwise from the north, are Malin Head, Fair Head, Belfast Lough, Carlingford Lough, Howth Head, Wicklow Head, Carnsore Point, Hook Head, Roches Point, Mizen Head, Valentia, Loop Head, Slyne Head, Erris Head, Rossan Point and Bloody Foreland. Strangford Lough and Dungarvan are also identified but rarely appear, and how the forecast is divided is a matter of timing and the choice of the duty forecaster – some choose Dungarvan over Hook Head for reasons as simple as their having grown up in Dungarvan!

The headlands, sea area and forecasting

Recently, I’ve visited each of the headlands, and what follows in this book is my experience of my time there, along with weather and the meteorology that goes along with it.

When deciding which headlands to use in a forecast, we divide the area based on the wind and try to draw as simple a picture of the changing scene as possible. We are conscious that in an emergency the mariner could be relying on listening to the message over long-wave radio in possibly rough conditions and, more and more often these days, possibly not in their first language either. There is no benefit to trying to capture every small change in wind direction and strength over the period at the cost of making the forecast unintelligible to the listener. To quote my algorithm lecturer from university – who was quoting someone far smarter – keep it simple, stupid. KISS.

But back to the headlands. We go clockwise around them and start with the area that has the strongest wind. That’s usually – but not always – in the west.

With depressions moving from the west to the east across the northern hemisphere, they have ‘free passage’ across the open Atlantic, skirting over the top of the Azores High (the anticyclone that is usually lying over the Azores) and making a direct line to Ireland. It is often at this point that the other blocking high-pressure area over continental Europe deflects the further passage east and the depression or storm moves northwards towards Norway, making for stronger winds on the west coast of Ireland than those experienced on the east. There is also the fact that as wind travels over land the effect of the friction of the land reduces the speed of the wind (and causes it to back somewhat). This means that the prevailing southwesterly winds along the coast of the west and south of Ireland are backed southerly or southeasterly and reduced along east-facing coasts.

We start with the strongest wind first, always conscious that a radio broadcast can drop at any point when out in turbulent waters, so it’s best to have the worst of the weather accounted for earliest. Once we have the spatial taken care of, it’s on to the temporal, because when forecasting the weather we have to consider variations over space and time.

It’s only a 24-hour forecast, but a lot can happen in 24 hours on the waters around Ireland. To make it even clearer, the 24 hours are broken up further, and to avoid ambiguity, we’ve defined words that in other contexts can mean just about anything. For example, when I ask my son when he plans to get around to cutting the grass and he says ‘soon’, I can work out that the grass may well be cut any time between St Patrick’s Day and Easter. When my publisher asks how soon they can expect the next chapter and I say it’s ‘imminent’, they might expect it by either the end of the week or the end of the month – depending on whether or not I’ll have to hand back my advance.

For the purposes of the sea area forecast, if a change is ‘imminent’ it is expected to happen within the next six hours; if a change is expected ‘soon’ it is expected between 6 and 12 hours; and ‘later’ means any time after 12 hours and before 24. Sometimes when something is predicted to happen more than 12 hours ahead but we’ve already used a ‘later’, you’ll hear things like ‘by this time tomorrow’ or ‘by the end of the forecast period’. It wouldn’t sound very lyrical or poetic to forecast something as going to occur ‘later later’.

The wind is forecast on an eight-point compass: north, northeast, east, southeast, south, southwest, west and northwest. Within the body of the forecast we use the Beaufort scale, while in the outlook we use descriptive language – light, moderate, fresh, strong, gale force, storm force, violent storm and, thankfully only once in a very long while, hurricane force.

Although it’s best to divide the sea area into as few groups as possible, two is most common, but sometimes there are three or as many as four. The Irish Sea can be either included in a group on its own or incorporated within an eastern group, and is often divided, commonly by terms such as ‘the Irish Sea north of Anglesey’.

We keep the weather simple – it’s not a case of some sunny spells and scattered showers at times in places. We stick with ‘fair’, ‘fine’, ‘cloudy’, ‘rain’, ‘drizzle’, ‘mist’ and ‘fog’, and include hazards such as ‘snow’ and ‘thunderstorms’ where necessary. Again, changes over time are indicated by ‘imminent’, ‘soon’ and ‘later’, and when the forecast might be complicated, sometimes added information is given by way of ‘in sea areas north/south/east/west of’ a relevant headland.

The language of the visibility section of the forecast is probably the easiest, although it’s equally important – it’s ‘good’ or ‘moderate’ or ‘poor’, often written as ‘poor in precipitation, otherwise good’. This commonly happens when the weather within an area is varying over time – for example with a frontal passage.

With the main body of the sea area done, there are just a few more details to complete the picture. A warning of heavy swells is issued – usually and quite commonly on Atlantic coasts, where the fetch can be from as far away as the Gulf of Mexico. ‘Fetch’ refers to the distance travelled over the oceans from the one direction.

Moving on to the surface of the ocean, conditions here are determined by winds. But waves are complicated and, like sound waves, can be distorted when layered one on the other. If this book inspires you to travel to the headlands of Ireland, take some time to sit and watch the waves come in. You’ll notice that periodically there’ll be higher waves, and if you study the ocean in an almost meditative state, you’ll become aware of the swell underneath the waves that ride over the top. When this swell rises above 4m, a warning is issued.

Descriptor

Wave height (metres)

Calm

0–0.1

Smooth (wavelets)

0.1–0.5

Slight

0.5–1.25

Moderate

1.25–2.5

Rough

2.5–4.0

Very rough

4.0–6.0

High

6.0–9.0

Very high

9.0–14.0

Phenomenal

>14.0

And then there are the ferry crossings – from Dublin, Rosslare and Cork to France and the UK. Again, it’s simple enough language, and we use ‘wavelets’, ‘slight’, ‘moderate’, ‘rough’, ‘very rough’, ‘high’, ‘very high’ and ‘phenomenal’. ‘Phenomenal’ is just that, waves of over 14m high that – when we view them from the safety of land – we can look at in awe and exclaim with all credibility, wow, that’s phenomenal! I don’t think I’ve used ‘phenomenal’ in the crossings, but I have seen it on my charts on more than one occasion on the west and southwest coasts. Some exceptional wave heights have been observed off our coasts over the years, and we’ll cover these in the chapters to follow.

The final section of the sea area forecast comprises the coastal reports. Th is is probably many listeners’ favourite part of the sea area forecast, curiously enough, particularly for those who are not mariners. This is also probably the most basic and intrinsic part of the forecast and dates all the way back to Vice-Admiral FitzRoy’s initial crusade to protect seafarers around the coasts. The barometers he put in place in those 15 coastal stations around the country measured the observed atmospheric pressure, and the port-masters sending back the information to Vice-Admiral FitzRoy would include other basic observed facts such as wind direction and speed, the weather, the visibility and the changes observed in the atmospheric pressure – whether it was falling, rising or steady. When collected together, these coastal reports can be used to draw the crudest of barometric charts, and this is how Vice-Admiral FitzRoy was able to construct his forecasts.