The Forecast for D-Day

During the early months of 1944, the allied forces, under Supreme Commander General Dwight D. Eisenhower, had begun to get the upper hand in the battle with Nazi

Germany, and plans were put in progress to invade occupied Europe using a massive sea-borne army launched from England.

Above - The Supreme Commander of the Allies, 5-Star General Dwight D. Eisenhower. (Image - Wikipedia Commons - click to enlarge)

This assault force would have to cross the English Channel before landing at several beachheads along the French coast near Normandy. The entire military operation was given the code name “Overlord” and the first day of the invasion was to be called “D-Day”.

The timing of the operation was paramount – for military reasons it had to be a time of full moon and spring tide which immediately defined several windows of opportunity that could be accurately predicted from astronomical and tide tables.

However, the other variable, weather, was not so easily predicted. If rough conditions developed whilst the invading armada was at sea, an absolute disaster could have followed. In particular, the landing barges, crammed with troops, were vulnerable to capsize in even moderate seas, and soldiers in full combat gear and carrying weapons, would have little chance. Eisenhower was acutely aware that in such circumstances, his massive army of some 200,000 troops could be decimated before even reaching the battlefield.

Predicting the weather on possible invasion dates therefore became of paramount importance. The period 4, 5 and 6^th June 1944 were periods of full moon and spring tides, and therefore became the focus for the weather forecasting team.

Predicting the weather in 1944 was much more difficult than today. There were no meteorological satellites, no computer simulations, and no organised network of automatic weather stations, as we see today. In addition, there was no international exchange of weather information because it was a time of warfare and weather conditions were classified as “secret”.

Meteorologists of the day relied mostly on “analogue” forecasting methodology. This consisted of

(a) Preparing today's weather map by delineating all the “highs”, “lows” and cold fronts.

(b) Manually searching the archives to find another similar map from the past.

(c) Looking at what weather followed in the historical example

(d) Assume the same would happen tomorrow.

The main problem with analogue forecasting was that it took little account of what was happening in the upper levels of the atmosphere. It was common to have two weather maps that were very similar but with different patterns in the upper winds, and this resulted in quite different weather to follow.

The forecasting team assembled comprised the top meteorologists from several countries. Group Captain James Martin Stagg, Superintendant of the Kew Observatory before the war was the head meteorologist, and he led the daily weather briefings that were held in the run-up to the invasion day.

The Allies Head of Meteorology, Group Captain James. M. Stagg

(Image from Wikipedia Commons - click to enlarge)

The American team included the well-known weathermen Benny Holzman and Irving Crick. The British had Charles Douglas, who was well known for his photographic memory of past weather events, and there was the brilliant Norwegian Sverre Pettersen, one of the foremost synoptic meteorologists of the day. In addition, experts from the Royal Navy were added to the team.

As the 4^th June approached, Stagg advised Eisenhower that there was a strong low-pressure cell located over the North Sea and that gale force westerly winds were likely over the invasion area. Stagg considered that the 4^th and 5^th would be too rough to attempt a crossing. After considerable consultation between the senior military officers and the meteorological team it was decided not to launch on either day.

The weather map for 9am on June 6, 1944. The invasion area was under the influence of a weak ridge of high pressure, but with a deep low to the north.

The red arrows indicate the direction from which the wind was blowing. (Click to enlarge)

But Stagg and his weathermen then gradually reached agreement that the 6^th may be suitable. The invasion area would lie between the strong “low” to the north and a weak high-pressure ridge that extended across Spain and southern France. The meteorological team considered that the influence of the high would be just strong enough to produce a temporary moderation in the weather. But it would be a close call – if the low moved even slightly southwards conditions across the channel could quickly collapse into gales and rough seas.

Eisenhower was faced with making one of the biggest decisions in history – stay or go in a marginal situation. His force was ready – a postponement would mean thousands of men would have to disembark, return to their land based units and wait for the next window of opportunity, increasing the chance of German readiness. To go would place his army at the mercy of a razor edge weather situation. He gave the order to go and 200,000 men went into action.

General Morgan, Eisenhower’s Chief of Staff, remarked to Stagg at the time

"Good luck Stagg: may all your depressions be nice little ones: but remember, we'll string you up from the nearest lamp post if you don't read the omens aright."

History reveals that the decision was the right one. The Germans had considered that the weather was too rough to attempt an invasion and were not on full alert and the allied forces were able to successfully cross the channel and establish beachheads. D Day was a resounding military victory and the Germans were put into a retreat that would ultimately lead to the collapse of the Third Reich in 1945.

American troops storm ashore from a landing craft, June 6th 1944

(Image - Wikipedia Commons - click to enlarge)

Interestingly the weather during the next window of opportunity, some two weeks later, was a disaster, with one of the worst summer storms in decades raging across the Channel. Eisenhower later confided to Stagg “I thank the Gods of War that we went when we did.”

General Dwight D. Eisenhower went on to become one of the most successful American Generals in history and ended the war a national hero. He became the 34th President of the United States and finally passed away, a revered figure, in 1969.

James Martin Stagg returned to civilian life after the war and became Director of the United Kingdom’s Meteorological Office. He was knighted in 1954 and as Sir J.M. Stagg was elected as President of the Royal Meteorological Society in 1959. He lived on until 1975 and goes down in history as one of the key meteorologists of the 20^th century.

Reference: The Forecast for Overlord, J. M. Stagg, Ian Allen, 1971.

Indigenous Weather Knowledge

One of the oldest ways of forecasting the weather comes from the indigenous peoples around the world, including the Australian Aborigines. These techniques evolved over many thousands of years and involved observing linkages between the weather and the behaviour of various plant and animal species.

Initially dismissed by western science, it has only recently been realised that there is an underlying scientific basis underpinning much of the indigenous weather knowledge (IWK), and a renewed interest has resulted.

There are many examples of IWK, both from Australia and around the world, and only a few are given here – the first three from Australia and the other two from external sources.

(a) The gidgee tree: This is a type of acacia native to inland Australia, and the belief is that when you can smell the gidgee tree, rain is on the way. It turns out that when the air humidity rises, the tree exudes a pungent smelling sap. And rising humidity is often associated with the onset of rain. This knowledge comes to us through peoples from various inland areas of NSW and Queensland.

(b) Flying foxes: In the Northern Territory, these large fruit bats move from inland areas to the riverbanks when the dry season is imminent and back the other way when the wet season is about to start. This behaviour is used by the local people to predict the changes of season.

A flying fox colony in northern Australia. (Image: Justin Welbergen, Wikipedia commons - click to enlarge)

(c) Brolga: The brolga is a large bird in the crane family. Its breeding is determined largely by rainfall and in the tropics takes place soon after the end of the wet season, from February to May. When breeding behaviour is observed early in the year it is taken as a sign that the dry season is imminent.


The mating behaviour of the brolga is used to forecast the onset of the dry season in tropical Australia.
(Image: Wikipedia commons - click to enlarge)

(d) Mango tree: A belief common to several Pacific Island peoples concerns the flowering of the mango tree – if this happens earlier then normal it is said to imply an increased number of tropical cyclones in the upcoming season. The modern explanation is that the mango tree will flower early if temperatures are warmer than normal and this occurs across island areas when the surrounding sea surface temperatures are warmer than normal. And warmer ocean temperatures promote increased tropical cyclone formation.
These conditions are characterised by what we today call the "La Nina".

The mango tree in flower - the timing of the blossoms is related to the intensity of the upcoming tropical cyclone season.
(Image: Wikipedia commons - click to enlarge)

(d) South American Sea Temperatures: For thousands of years, native Peruvian fisherman trolled for anchovies, a cold water fish that thrives off the coast of South America. However they observed that during some years warm water develops along the coastline, killing the anchovies by the hundreds of thousands. The local peoples monitored the ocean temperatures by immersion and “feel”, and when these warmer waters were detected, they planted increased crops of sweet potatoes in anticipation of reduced anchovy catches. Today we know this warm water development off the coast of South America as "El Nino".

Indigenous weather knowledge is a fascinating topic and because of its great antiquity forms a valuable goldmine of information that can be well integrated into today's scientific knowledge.

The Bureau of Meteorology web site contains some fascinating information on this subject at:

http://www.bom.gov.au/iwk/

For some other information on the more usual ways of defining the seasons go to

http://passingparade-2009.blogspot.com.au/2012/05/defining-seasons.html


Reference: The Complete Book of Australian Weather, Richard Whitaker
Allen and Unwin, 2010

The Weather Channel Web Site

Recently the Weather Channel in Australia spent and great deal of time (and money!) doing a complete remake of its website.

You can see the result at

http://www.weatherchannel.com.au

It's a revolutionary way of retrieving weather information from the Internet, utilizing a single page from which all other content can be accessed. This means that you don’t have to move from page to page – it’s simple and easy.

A really great feature is being able to go full screen with the satellite images, radar, and lightning tracker. You can also zoom in and out by rolling your mouse wheel – really quick and useful.

The cloud resolution is great – you can see fog clearly, which is often difficult in conventional displays.

Fog can clearly see seen on the new Weather Channel interactive map.

(Click on image to enlarge)

Some of the key issues the page offers are:

All your local weather information is combined into one page. There’s no more hunting through pages of content – you’ll have all the information you need – whether it’s the ten-day forecast, the radar or the rainfall probability at a single glance.

It offers you instant access to your local weather- the computer detects where you are, and instantly displays the weather information for that location.

A revolutionary Interactive map – displays satellite and radar data from both the past and future 24 hours and so you can track how storms move over time. You can manipulate the map to move between different locations, zoom in and out and even make it full-screen for a truly breath-taking experience of the weather.

It’s advantages to users are:

Ease of use –
No more hunting through layers of content to get the weather forecast, weatherchannel.com.au displays all your essential weather information in one page – so you’ll have everything you need in a single glance.

Furthermore, whilst other websites divide up the radar views into separate pages, The Weather Channel site has combined all radar information in their truly interactive map, meaning that users can watch the rain move across broader areas in a single glance.

Speed –
The new website is fast to use – thanks to cutting-edge geotargeting technology. It recognises where you are accessing the site from and takes you instantly to the weather information for your location.

Increased Interactivity –
Weatherchannel.com.au is the first Australian weather website to feature a comprehensive interactive weather map which combines weather observations and forecasts, radar, satellite and lightning information all in the one view. Users have the option to view the map full screen and can easily zoom in and out to view weather activity at both a national and more local level.

Jet Streams and Tropical Cloudbands

Jet streams

Early in the twentieth century, meteorologists predicted that there would be high-speed rivers of air in certain areas of both hemispheres at around the area of the tropopause, approximately 10 to 15 km above the surface. They posited that these would be a consequence of the physics of the rotating Earth–atmosphere system.

The German meteorologist H. Seilkopf is believed to have first used the term “strahlstromung” (jet stream) in a treatise on upper atmospheric flow in 1939. However, it was not until World War Two that anyone directly encountered these ‘jet streams’. Aircraft on high-level bombing missions over Europe and Japan encountered tremendous headwinds on occasion, up to 350 km/h, which was almost as fast as the aircraft of the day could fly. Some of the planes were virtually stationary in the sky as they flew head on into the jet streams.

Today we know that jet streams are indeed real, and they are an important part of the motion of the atmosphere. There are two main jet streams in each hemisphere, called the polar jet and the subtropical jet. They rotate in a general west to east direction high above Earth, but they frequently twist and turn, producing meanderings of north and south winds on occasion. There are times where the polar jet and subtropical jet can intersect, producing highly complex effects in the upper troposphere.

The subtropical jet is found at latitudes around 25 to 35 degrees north and south of the equator, and the polar jet between the 50 and 60 degree latitudes. All these jet streams occur at the boundaries of cold and warm air in the upper atmosphere and are typically 1.5–4.5 km across.


A jet stream made visible by cloud as it crosses eastern Canada in May 1991. Jet streams can make a significant difference in flying times across Australia. If favoured by a jet stream, a flight from Perth to Sydney can take half an hour less than the reverse trip, Sydney to Perth. (NASA Space Shuttle image - click to enlarge)

They are of considerable importance in the development and steering of low-pressure systems, and meteorologists pay careful attention to their location and general movement. The aviation industry is also very interested in jet streams because of their effect on flight times. For example, when travelling from Perth to Sydney, ‘hitching a ride’ on the high-level subtropical jet stream can save significant time and fuel. Conversely, flying into the jet stream will slow the ground speed of the aircraft considerably, and in many cases the captain will attempt to fly above or below it to save time.

Another problem with the jet stream is its association with high-level clear air turbulence—or CAT—which can be uncomfortable or downright dangerous for passenger aircraft. Because jet streams are zones of high-speed winds running within the broad-scale atmospheric flow, there are surrounding regions where the wind speeds change quickly with both height and horizontal distance. This is called wind shear and a high-speed aircraft flying through it will experience ‘bumpiness’, something like a car driving over a series of potholes. This is called turbulence.

In most cases turbulence is only slight, but sometimes severe buffeting can occur, sufficient to throw objects around the cabin and injure passengers.

Tropical cloud bands

Jet streams play an important role in the generation of tropical cloud bands that periodically develop near the equator and then move to the mid latitudes—from the southwest in the northern hemisphere and the northwest in the southern hemisphere.

These cloud bands are the result of complex interaction between warm sea surface temperatures and upper wind patterns, notably the subtropical jet streams. They are important sources of rain in some mid-latitude areas, including Australia, where they are known as northwest cloud bands.

A northwest cloudband streams across Australia on 30th July 2008.
(Bureau of Meteorology image - click to enlarge)

In a large part of western and central Australia, more than 60 per cent of the April–October rainfall is contributed by northwest cloud bands that form to the south of Indonesia before streaming in from the northwest to form a cloud ‘conveyor belt’ that can be between 3000 and 8000 km long.

When a northwest cloud band interacts with a cold frontal system over southern areas of Australia, significant inland rain can result.

Reference: The Complete Book of Australian Weather by Richard Whitaker
Allen and Unwin 2010, ISBN978 1 74175 734 7

Bob Beamon's Leap Into History

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It was the afternoon of October 18^th 1968, and the occasion was the long jump final of the Mexico City Olympic games. Bob Beamon, the United States champion, stood at the beginning of the long jump runway, eying the raked sand landing pit some 50 metres away.

A tall, lean and muscular man, Beamon was one of the favourites for the event, but not the world record holder – this had been set at 8.35 metres by the Russian athlete Igor Ter-Ovanesyan almost exactly a year before.

Beamon began his run, accelerating smoothly to top pace and hit the take off mark absolutely flat out and in perfect balance. Soaring into space he seemed to briefly defy gravity and float above the sand before returning to earth with a textbook landing. Even to the untrained eye it looked to be a massive jump, but it was destined to be far more than that – it became one of the defining moments in the history of track and field.

His leap was so huge that that it was beyond the range of the special optical device that had been installed to measure the jumps – instead, stunned officials scrambled to measure the distance with a tape. The result was electrifying – a new world record of 8.90 metres was flashed up on the scoreboard. And not only a new record but an absolute demolition job – nobody in history had jumped anywhere near this distance before.

Bob Beamon's jump was a record in terms of distance and also in terms of the amount by which the previous record was broken. Image from Wikipedia Commons

(Click to enlarge)

Normally, in the long jump, when a new record is set, any improvement over the old figure is measured in small increments. But Beamon’s jump raised the distance by an astonishing 55 cm – by far the biggest increase in recorded history.

The rest of the meeting was almost an anticlimax – rain washed through the stadium soon after and second place went to Klaus Beer, the East German, with a leap of 8.19 metres – an astonishing 71 cm short of Beamon’s jump. Bob Beamon finished the day with an Olympic Gold medal, a world record and one of the most remarkable performances ever recorded in the history of athletics.

So how was he able to jump so far on that afternoon? A great deal of study and investigation followed to try and account for his phenomenal performance.

Mexico City lies at an altitude of 2300 metres where the atmosphere is only about 75% as dense as that at sea level, meaning that Beamon experienced correspondingly less air resistance. In addition, he jumped with a “tailwind” which also assisted him – subsequent studies showed that these two factors of altitude and wind assistance could have provided him with a 31 cm advantage compared to a similar jump in still conditions at sea level. This still leaves unexplained a distance of 24 cm – the balance of the 55 cm by which he broke the world record.

Technically, Beamon’s jump was near perfect – his run up was smooth and he hit the take off board at full pace without having to lengthen or shorten his stride. Post analysis of the jump using both still and “movie” images show that he would have cleared a horizontal bar set at 1.7 m over the middle of the pit, which is a phenomenal height for a long jumper. His style through the air was textbook – he adopted a classic aerodynamic position that minimised air resistance and the landing was also ideal with maximum extension achieved without toppling backwards.

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But even all these factors do not adequately explain the enormity of his achievement – perhaps it is only the human spirit, that can, on special occasions, produce superhuman results – that provides the answer.

Bob Beamon’s jump stood as the world long jump record for 23 years until exceeded by 5 cm in a jump by Mike Powell in August 1991. However it still stands as the Olympic record – 44 years later as of 2012.

The gold medal for the London Olympic games was won by Greg Rutherford of Great Britain with a great leap of 8.31 m. However this would not have come close to Bob Beamon's jump.

If we rank all the long jump world records since 1900 in order by the amount that each broke the previous record, we obtain the following table:

1. Robert Beamon (USA) 55 cm 1968

2. Jesse Owens (USA) 15 cm 1935

3. William Hubbard (USA) 13 cm 1925

4. Edward Gourdin (USA) 8 cm 1923

5. Ralph Boston (USA) 8 cm 1960

6. Robert LeGendre (USA) 7 cm 1924

7. Chuhei Nambu (JPN) 5 cm 1931

8. Michael Powell (USA) 5 cm 1991

9. Ralph Boston (USA) 4 cm 1961

10. Sylvio Cator (HAI) 3 cm 1928

11. Ralph Boston (USA) 3 cm 1961

12. Igor Ter-Ovanesyan (URS) 3 cm 1962

13. Ralph Boston (USA) 3 cm 1964

14. Edward Hamm (USA) 1 cm 1928

15. Ralph Boston (USA) 1 cm 1965

16. Ralph Boston (USA) 0 cm 1964 (equal WR)

17. Igor Ter-Ovanesyan (URS) 0 cm 1967 (equal WR)

We see from this analysis that Bob Beamon’s jump stands alone. His performance earned him the title of Track and Field Athlete of the Year for 1968 and was later named as one of the five greatest sporting achievements of the 20^th century by Sports Illustrated.

For a great vision of the now legendary jump see

http://www.tumblr.com/tagged/bob%20beamon?page=20

and

http://www.youtube.com/watch?v=DEt_Xgg8dzc

For some information on the world high jump records see

http://passingparade-2009.blogspot.com/2011/10/how-high-can-humans-jump.html

The Race of Death

By world standards, mountains in Australia are not very tall with the highest peak being Mount Kosciusko at only 2235 metres. However, extreme conditions can occur across the mountain ranges over south-eastern Australia, particularly in the winter months when quite heavy snow can fall over widespread areas. This has led to tragedy in the past, and some hard lessons have been learned about life in the high country.

Image: Mount Wellington towers above Hobart, often carrying a mantle of snow during the winter months.

Image from Wikipedia commons - click to enlarge.

Mount Wellington forms a picturesque backdrop to the City of Hobart, rising to a height of 1270 metres, and often with its peak covered in snow during the winter months. However, because of its southerly latitude, snow producing cold fronts racing up from the far Southern Ocean can reach the area at any time, even during the summer, triggering extreme changes in temperature across the area. When a strong cold front moves through Tasmania snow can extend down to quite low levels, with several recorded cases of snow actually reaching sea level around Hobart.

It was Mount Wellington, with its notoriously capricious weather that formed the stage for a gruelling athletics race in 1903, a race that was to end in a double tragedy.

In the early 1900’s there was an Australia-wide athletics craze, with numerous running and walking competitions staged around the country, involving both sprinting and distance events. Unlike today’s fun running phenomenon, these events normally involved trained and sometimes professional athletes, with prizes given and a good deal of public betting on the side.

However the first major race up Mount Wellington was an all-amateur affair, organised by the Tasmanian Amateur Athletics Association, and with the first prize not money, but a brand new double barrelled shotgun presented by the sponsor Watson Whisky.

The race was organised for Saturday September 19, 1903, and ran from Lower Elizabeth Street to the top of Mount Wellington and back – a distance of some 27 kilometers. The format was what was called a “Go As You Please” race, which meant that the route the runner elected to take was optional - provided he reached the checkpoint at the top of the mountain, he could go any way he wanted.

On the morning before the race, the weather was described as “very unsettled”, with snow drifting down to low levels on the mountain. There was talk of postponing the start, but eventually the field got under way in the early afternoon, with 39 out of the 70 original entrants beginning the race. The pace was a cracker out of the city but naturally began to slow as the runners began the arduous climb up the side of the mountain.

The Organ Pipes - a distinctive rock formation near the summit. Image from Wikipedia commons - click to enlarge.

Then, only part of the way through the climb, it began snowing and the athletes, only lightly clad in athletic singlets and shorts, found themselves in freezing conditions, with a strong south-west wind producing a chill factor that effectively dropped the temperature much further. The going became too tough for several and only 23 out of the 39 starters reached the pinnacle and began the downhill run home.

One member of the group of officials at the summit reported that “He had never met with worse weather on the mountain. With the heavy snow beating on them,(the athletes) their clothes got frozen hard”. Leading at the half way mark was a runner called Charles Beard, but he was followed closely by a group which consisted of Betts, McDonald and Cockshutt. Another athlete, Mark Richards, also reached the summit but complained of feeling faint and dizzy. He was about to drop out but was “encouraged by another competitor” and was persuaded to run on.

As a result of the steep downhill grades on the return journey, the pace picked up considerably, but because of the freezing conditions many of the athletes became exhausted and dropped out. More than half of the 23 men who reached the summit failed to reach the finish, and only a small band eventually raced into the city, applauded by a large crowd. The eventual winner was Cockshutt in the very respectable time of 2hr 44 min.

However the euphoria of the finish of the first organised race up Mount Wellington was soon eclipsed by the news filtering back from the mountain; Mark Richards had collapsed and died part way down, and another athlete, George Radford, was missing. The local police, together with the race promoters, immediately organised search parties, and these continued in failing light and falling snow until well after midnight, but no trace of Radford was found. Next morning the search resumed at sunrise, and a little later, Radford’s body was found in the snow on the “Old Fingerpost Track” where he had fallen backwards and frozen to death.

This double death toll cast a pall of gloom over the race as well as the organisers and a full coronial enquiry was ordered. This found that both Richards and Radford had died from a combination of heart failure and prolonged exposure to below freezing conditions.

Such a tragedy is unlikely to happen today. Recognised distance running events involving either elite athletes or “fun runners” are carefully planned and have medical assistance available to all competitors. In addition, the weather forecasts are routinely monitored, and if extreme conditions, such as very hot or very cold temperatures are forecast, race organisers will incorporate this into their planning.

As far as Tasmania is concerned, not only Mount Wellington, but the state as a whole, can experience great temperature variations. Cold outbreaks can produce snow across many parts of the Tasmanian highlands even during the summer months, and the Bureau of Meteorology issues “Bushwalker’s Alerts” when such a change is expected.

Today the Radford Track on Mount Wellington is both a memorial and a reminder of the tragic events of September 1903.

Reference: Australia's Natural Disasters, Richard Whitaker, New Holland Publications, 2005

The Naming of Tropical Cyclones

Photograph: HMAS "Arrow" lies wrecked in Darwin Harbour following tropical cyclone "Tracy" in December 1974. Image: Wikipedia Commons - click to enlarge

Whilst many of the famous tropical cyclones in Australia’s history are instantly recognised by the names they were given, such as Tracy, Althea and Trixie, some of our most intense cyclones were never named at all.

The reason for this is tied up in the history of the naming of cyclones in Australia, which is an interesting story in itself. Clement Wragge, the rather eccentric Queensland Government Meteorologist from 1887 to 1902, is thought to have been the first person in the world to name tropical cyclones.

He called them after letters from the Greek alphabet, figures from Greek and Roman mythology, feminine names and also the names of some of the politicians of the day, including Drake, Barton and Deakin. Wragge considered that both politicians and tropical cyclones were national disasters.

In 1902, the Member for Werriwa was the Honourable Mr. A.H.Conroy, who somehow had incurred Wragge’s displeasure because he featured in several cyclone warnings. These included “Conroy, looking nasty, is coming along the coast” and “Conroy, black and treacherous, is likely to cross the Southern District…”. Justifiably miffed, Conroy dismissed Wragge as “an advertising scientist”.

After Wragge had left the meteorological scene in 1908, the naming of tropical cyclones lapsed and was not resumed by the Bureau of Meteorology in Australia until 1963. Then only feminine names were employed, but after complaints that this practice was discriminatory, both male and female names were used from 1975 onwards.

As a result of all this, cyclones that occurred between 1908 and 1963 were generally not given a name and these included some major storms that created massive damage and considerable loss of life. A powerful cyclone devastated Mackay in January 1918, killing 30 people and destroying some 30% of the housing in the area. And in 1954 a cyclone struck the Gold Coast of Queensland with 26 people perishing and hundreds of houses destroyed in the general area. Neither of these cyclones was named.

Tropical cyclone "Ingrid" threatened the Queensland coastline during March 2005.

(NASA image) - click to enlarge

Today, the names of tropical cyclones come from a list maintained and updated by the Bureau of Meteorology according to quite a strict protocol.

This contains five main guidelines that are called the “Tropical cyclone naming policy” and these are:

* Tropical cyclone names in each list are alternate male and female

* Names of cyclones that have already significantly affected the Australian region cannot be used again – for example “Tracy”.

* If two or more cyclones are occurring simultaneously, similar sounding names (for example June & Jane) are avoided to minimise confusion

* Names should not be capable of being construed to subject the Bureau to criticism or ridicule (for example naming a sequence of cyclones after politicians)

* Lists of names are coordinated with neighbouring meteorological services to avoid duplication

These guidelines, together with the current list of names being used, can be found at

http://www.bom.gov.au/cyclone/about/names.shtml

Tropical revolving storms – that we call tropical cyclones in Australia - are referred to as “hurricanes” in the USA and “typhoons” in much of Asia.

Hurricane derives from the South American Carib word “Hurican” meaning God of Evil, and typhoon originates from the Chinese “tai’fung” meaning Great Wind.

Reference: Australia’s Natural Disasters, Richard Whitaker (New Holland Publishers) 2005.