East Coast Lows. The Good, The Bad and The Ugly.

27 May 2009 0 Share

East Coast Lows. A weatherman’s woe, a fisherman’s foe, a surfer’s favourite show.

– By Coastalwatch editor Ben Horvath.



Noosa 23-25 May 2009
a Tim Bonython film

Mindless Boiling Pot at Noosa on Saturday May 23.

Mindless Boiling Pot at Noosa on Saturday May 23.

Perfect pit at Noosa on Friday May 22.

Perfect pit at Noosa on Friday May 22.

Whilst East coast Lows (ECL’s) may be a weatherman’s woe, surfers literally rejoice and worship their curvy isobars the moment they spot one developing in the Coral or Tasman Sea.

So while rock fishermen, small boating enthusiasts and insurance companies despise ECL’s, surfers literally rush off to wax their boards in anticipation of big, long period swell lines rolling into their favourite big wave spot.

All roads led to Noosa Heads during the most recent swell event. Since the ECL that formed just off the coast of SE Qld on Thursday May 21 there have been some great waves within the sheltered confines of Noosa’s pointbreaks. Further south the more open exposed beaches between the Gold Coast and Sydney have been bombarded by howling onshore Easterly winds limiting surfable options to sheltered novelty breaks inside harbours and massive protective headlands. There were some fun surfable novelty waves inside Port Stephens, Broken Bay, Sydney Harbour, Botany Bay and Port Hacking on Saturday May 23, but most open ocean beaches were a wild, windblown mess.

The weather maps on the biggest days Thursday May 21 through to Saturday May 23, 2009. Snapper was 12 feet plus on Friday May 22.

The weather maps on the biggest days Thursday May 21 through to Saturday May 23, 2009. Snapper was 12 feet plus on Friday May 22.

 Coastalwatch virtual buoys swell chart documenting the May 21 to 25 swell event.

Coastalwatch virtual buoys swell chart documenting the May 21 to 25 swell event.

What is an East Coast Low?

East Coast Lows (ECL) are intense low-pressure systems which occur on average several times each year off the eastern coast of Australia, in particular southern Queensland and NSW. Although they can and do occur at any time of the year, they are more common during autumn and winter with a maximum frequency in June. East Coast Lows will often intensify rapidly overnight making them one of the more dangerous weather systems to affect the NSW coast.

East Coast Lows may form in a variety of weather situations. In summer they can be ex-tropical cyclones. At other times of the year, they will most often develop rapidly just offshore within a pre-existing trough of low pressure due to favourable conditions in the upper atmosphere. ECL's may also develop in the wake of a cold front moving across from Victoria into the Tasman Sea. The sea surface temperature gradients associated with the warm eddies of the East Australian Current also contribute to the development of the lows.

The gales and heavy rain occur on and near the coast south of the low centre, while to the north of the low there can be clear skies. The challenge for forecasters is to accurately predict the location and movement of the centre of the low.

Pauline Menczer's wayward tree

Pauline Menczer's wayward tree

Why are they dangerous?

ECL’s can generate gale or storm force winds along the coast and adjacent waters. Heavy widespread rainfall leading to flooding is not uncommon and big long period ocean swells can cause damage and severe erosion to the coastline.

Falling trees and flash flooding have caused fatalities on the land, many small craft have been lost off the coast and larger vessels have run aground during these events.

The swell made it all the way down the south coast of NSW. Waves washing over break wall at Wollongong Harbour on Sat May 23, 2009.

The swell made it all the way down the south coast of NSW. Waves washing over break wall at Wollongong Harbour on Sat May 23, 2009.

How often do they form and is there a trend?

On Monday evening May 18, Ben Macartney and I attended an extremely interesting presentation organized by The Maritime Panel in Chatswood. The guest speaker was recently retired senior severe weather Meteorologist with the Bureau of Meteorology Brisbane Jeff Callaghan.

Jeff said, “The east coast of Australia has experienced, since 1977, a relatively quiet period in relation to the impact from damaging cyclones and East Coast Lows. Over the same period there has been a large increase in the coastal population and in the number of people involved in marine activities. Some events, which occurred from the 1950s to the mid seventies repeated today, would have catastrophic consequences.”

Jeff had accumulated much scientific evidence that the frequency of ECL’s before 1977 was much greater than post 77, though Jeff did suggest we may now be moving into a new active phase.

Jeff discussed the possible reasons for these large periods of enhanced activity. He also pointed out the most damaging of these coastal storms since the East Coast Low (ECL), which Captain Cook encountered, in May 1770 off Point Danger. Jeff examined the Dandenong Gale (1876); tropical cyclones Buninyong (1893), Mahina (1899), The 1916 Clermont Cyclone, The Two 1918 cyclones, The 1929 Launceston Floods, The Sydney Cyclone (1950), The June 1950 ECL, The 1955 Maitland Floods, 1967 Qld /NSW beach erosion storms, The 1974 Cyclones and Sygna Storm, The August 1986 Sydney ECL, The 1998 Sydney Hobart Storm, and the June 07 Pasha Bulker ECL.

Jeff finally pointed to some recent developments that suggest we may have already begun a new active phase. Possible reasons that this may be so are a recent decline in the serial El Nino episodes and a spate of recent coastal storms such as severe tropical cyclones Ingrid (2005), Larry (2006), Monica (2006), Hamish (2009), ECLs SE Qld and N NSW (2004, 2005, 2006, 2007,2008), Newcastle ECL (2007) and record Queensland floods (2008 and 2009).

Jeff has joined the Coastalwatch team. Jeff’s first feature analysing the recent East Coast Low (May 20 – 25) will be posted today as a follow up to this introductory piece. Look out for a new series of articles looking back at the most memorable East Coast Lows in history.


The view from above D'bah of the massive Friday morning May 22, 2009 swell.

The view from above D'bah of the massive Friday morning May 22, 2009 swell.

What is the difference between an East Coast Low and a Tropical Cyclone?

Tropical Cyclones develop over very warm tropical waters where the sea surface temperature is greater than 26°C. They have relatively long life cycles, typically about a week, and severe tropical cyclones (category 3 or greater) can produce significant property damage with wind speeds over 180km/h near the centre, heavy rainfall and coastal inundation through storm surge. Tropical Cyclone "Justin", which affected the Queensland Region in March 1997, lasted for 18 days!

East Coast Lows generally have much shorter lifetimes than Tropical Cyclones and last only a few days. They develop over the Tasman Sea close to the NSW coast and can intensify rapidly in the overnight period. Unlike Tropical Cyclones, where the warm seas provide the energy source, East Coast Lows are driven by the temperature gradient between the Tasman Sea air and cold air in the high levels of the atmosphere over the continent. They can produce gale to storm-force winds, very heavy rainfall and in some cases coastal inundation. While maximum wind speeds recorded are lower than in severe tropical cyclones, a gust of 165 km/h was recorded at Newcastle associated with the east coast low that sunk the bulk carrier Sygna in 1974. During the first of the ECLs in June 2007, when the bulk carrier Pasha Bulker ran aground, gusts of 105 km/h at 6:21am on 8 June and 124 km/hr at 1:32am on 9 June were recorded at Newcastle.

Kelly Slater as seen from the water at Kirra in April 2009. Kelly said, 'The East Coast storms this autumn produced the best waves at Kirra in a decade.'

Kelly Slater as seen from the water at Kirra in April 2009. Kelly said, 'The East Coast storms this autumn produced the best waves at Kirra in a decade.'

Surfing deep inside Sydney Harbour at Nielsen Park on Saturday May 23, 2009.

Surfing deep inside Sydney Harbour at Nielsen Park on Saturday May 23, 2009.

The Captain Cook cruise boat passes a large crowd of Sydney Harbour surfers seeking protection from the wild open ocean swells bombarding Sydney's open beaches on Saturday afternoon May 23.

The Captain Cook cruise boat passes a large crowd of Sydney Harbour surfers seeking protection from the wild open ocean swells bombarding Sydney's open beaches on Saturday afternoon May 23.

Surfing novelty waves like this wave inside Broken Bay, Pittwater, is a buzz when there is nowhere to surf on the northern beaches.

Surfing novelty waves like this wave inside Broken Bay, Pittwater, is a buzz when there is nowhere to surf on the northern beaches.

When were most recent major East Coast Lows?

Obviously the ECL that formed off SE QLD on Thursday May 21 that delivered record rainfall gale force winds and massive seas right up and down the East coast is the most recent example of a destructive ECL still fresh in everyone’s mind. It wasn’t a truly memorable storm as far as board riders are concerned, because winds were unco-operative gale force Easterlies for the most part. There was literally nowhere to hide. Noosa was virtually the only protected option on the Eastern seaboard and it turned on some great waves.

Back on April 1, 2009 a similar, though slightly less intense ECL delivered big swells right along the East Coast. Balmoral and Nielsen Park in Sydney Harbour had surf able waves. Noosa was again the place to be.

The two best days of surf in NSW so far this year were long period ocean swells courtesy of offshore ECL’s. Anzac Day and May 13 being the standout days of 09 so far.

The best surf producing ECL’s in SE Qld and northern NSW so far in 2009 were cyclones.

Cyclone Hamish produced some incredible waves on the Gold Coast from March 9-11, 2009.

Not long after, Jasper the Friendly Cyclone produced what 9 times world champion Kelly Slater called, “The best Kirra in a decade” from March 30 – April 2, 2009.
The three best all time ECL’s in modern historic surf folklore.

June 2007
June 07 – An unprecedented succession of 8 ECL’s in 4 weeks set a new benchmark in surfing history on Australia’s East coast. I compiled a feature in the August 07 issue of Tracks outlining the remarkable period which began with the “Pasha Bulker” running aground in huge storm surf off Nobby’s Beach Newcastle on June 8, 2007.

There were in fact 8 separate low pressure systems that penetrated Sydney’s swell window in June 07(that is if you include the small to medium Sth that hit on June 1 and 2. That’s an unbelievable average of two low pressure systems a week sending swells our way.)

A whopping 510.6mm of rain fell on Sydney, making it the second wettest June on record. There were 16 rain days, and only 140 hours of sunshine out of a possible 300. The average maximum temperature of just 16.8 degrees was the coldest June in 18 years. All of the above can of course be attributed to the series of east coast lows that also delivered the epic waves.

Go to:
East Coast: June 2007 Meltdown for a comprehensive feature on the historic June 07 swells. Look out for Jeff Callaghan’s comprehensive analysis of June 07 for Coastalwatch in meteorological terms in an upcoming feature later this year.


July 2001.

July 01 – “The Big East” – A young Mick Fanning and Kieren Perrow threaded through endless long barrels at Lennox Head as every point and reefbreak between Burleigh and Bega pumped. It was the biggest and cleanest east swell since 1983. (Look out for a detailed retrospective feature on Coastalwatch later this year.)


June 1983
“The Swell – June 83.” Tim Bonython made a great film about this historic swell. Tom Carroll, Derek Hynd, Mike Newling and Micheal Novakov scored endless tubes at North Narrabeen. Every point, reef and beach break in NSW pumped for days on end. (We will be posting a cool feature on Coastalwatch this June in memory of one of the best swells ever.)

When were the major historical East Coast Lows in a destructive sense?

2 October 2004

Moderate rainfalls were recorded in the Illawarra, Central Tablelands and South Coast and isolated heavy falls over parts of the Metropolitan and Hunter districts. The highest were 132 mm at Wyong and 62 mm at Kurranjong Heights and 89 mm at Castle Cove.
Gale to storm force winds were recorded along parts of the coast.
Mean wave heights off Sydney were 5m with around 10m maximum wave heights and heavy swell on October 1 and 2.
Central pressure dropped 6hPa from about 1004hPa to 998hPa over 24hr period to 10am 02 October.

27-28 July 2001
Showers developed along the coast, with an isolated heavy fall of 91mm at Nelson Bay on the 28th. Rainfall in Sydney area varied from 10-30mm.
Strong southerly winds at 50-60km/h reached gale force at times with gusts over 100km/h in coastal Sydney.
Significant Wave height from 4 to 6 metres.
An inland low-pressure trough deepened under an upper air disturbance. Central pressure dropped 16hPa from 1011hPa at 10am on the 27th to 995 at 10am on the 28th.

7-8 August 1998
Rainfall totals over the four days (6-9 August) were greater than 300mm at many locations in the Metropolitan and Illawarra districts.
Highest totals were 420mm at Beaumont and 401mm at Kangaroo Valley.

30-31 August 1996
Central pressure dropped 12hPa in 12 hours between 9pm and 9am
Highest rainfall total 386mm at Darkes Forest.
Cost 2 lives and caused almost $20 million damage.
Maximum wind gust was 64knots near Wollongong

5 August 1986
24 hour rainfall totals: over 300mm in Sydney area.
Major flooding on the Nepean-Hawkesbury and Georges Rivers
Mean wind speed up to 40 knots at Norah Head
Observatory Hill - Highest daily rainfall total on record: 328mm.

26 May 1974 - "Sygna" storm
Wind gusts at Newcastle Nobbys around 165 km/hour.
The wreck of the Sygna, driven onshore during the storm, still lies on Stockton Beach, near Newcastle.

20 August 1857 - "Dunbar" storm
The Dunbar, a sailing ship carrying 122 people from England, was wrecked off South Head while trying to seek shelter in Sydney Harbour. There was only one survivor.

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