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Tropical Cyclone Trends In Australia

October 3, 2017

By Paul Homewood

Hurricanes have been a topic of attention recently for obvious reasons.

I have done a lot of analysis of Atlantic storms, but elsewhere there is much less historical data, due to the lack of monitoring at the time.

Until recently, many, probably the vast majority of, tropical cyclones blew around in the middle of the vast Pacific with little or no attention at all. Where they did affect land, there was rarely any proper equipment around to properly measure them.

The Australian BOM has put together a history of TCs in their region, beginning in 1970, when satellite coverage began:

Tropical cyclones in the Australian region are influenced by a number of factors, and in particular variations in the El Niño – Southern Oscillation. In general, more tropical cyclones cross the coast during La Niña years, and fewer during El Niño years.

Analysis of historical tropical cyclone data has limitations due to a number of changes in observing practices and technology that have occurred over time. With new and improved meteorological satellites our ability to detect tropical cyclones has improved, as has our ability to differentiate tropical cyclones from other tropical weather systems such as monsoon depressions, which in the past may have been incorrectly named as tropical cyclones. A particularly important change occurred in the late 1970s when regular satellite images became first available from geostationary satellites above the Earth’s equator.

The time series of analysed tropical cyclone activity in the Australian region (south of the equator; 90-160°E) show that the total number of cyclones appears to have decreased. However, there was a change to the definition for tropical cyclones in 1978 which led to some systems which would previously have been classified as tropical cyclones instead being considered sub-tropical systems. This contributes somewhat to the apparent decline in total numbers.

The number of severe tropical cyclones (minimum central pressure less than 970 hPa) is dominated by variability with periods of lower and higher frequencies of occurrence. There is less confidence in the earlier intensity data with continuous satellite coverage commencing in 1979.

 

image

http://www.bom.gov.au/cyclone/climatology/trends.shtml

 

Accepting what they say about the pre-1979 figures, there is certainly no increasing trend, either for total or severe cyclones.

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11 Comments
  1. RAH permalink
    October 3, 2017 11:33 am

    “Tropical cyclones in the Australian region are influenced by a number of factors, and in particular variations in the El Niño – Southern Oscillation. In general, more tropical cyclones cross the coast during La Niña years, and fewer during El Niño years.”

    It seems that La Nina conditions cause increased weather extremes about everywhere. The US model, which has been out ahead of the European and others in that aspect, is now predicting a pretty deep La Nina coming.

    Thus we can expect that next years Atlantic Hurricane season will be as active or even more active than this years.

    For we that live in the US that live in the Midwest or North East winter precipitation will probably be considerably higher than average. The long range winter forecast at Weatherbell.com reflects that forecasting 33% higher than normal snow for those regions.

    A little OT shout out for something that generally goes without much notice.
    The US Navy has two hospital ships.  One of them, the USNS Comfort, deployed from Norfolk Sept, 29th bound for Puerto Rico.  The ship carries over 800 medical personnel and support staff.  
    The other Hospital Ship is the USNS Mercy.  It works in the Pacific. The two ships are virtually identical.  Both were converted from oil tankers.  Both have considerable medical capabilities and 1,000 beds.

    Both ships deploy on humanitarian missions of mercy every year, including providing medical support for areas hit by tropical storms where medical support is needed. It is all done with little notice or fan fair.

  2. October 3, 2017 1:08 pm

    I tweeted it.

  3. October 3, 2017 1:12 pm

    Paul, please note that there is somewhat of a rising trend in the severe fraction

    • A C Osborn permalink
      October 3, 2017 2:15 pm

      No there isn’t, there was until the middle of the graph and then a dropping trend since.
      I wouldn’t draw a straight line through that lot.

  4. Broadlands permalink
    October 3, 2017 1:35 pm

    There are some older data on typhoons, complied by Chu…

    ftp://ftp.library.noaa.gov/docs.lib/htdocs/rescue/mwr/053/mwr-053-01-0001.pdf

  5. October 3, 2017 2:09 pm

    Reblogged this on Climate Collections.

  6. Curious George permalink
    October 3, 2017 3:53 pm

    You are not progressive at all. Progressives know that hurricanes and cyclones are climate, not weather.

  7. Graeme No.3 permalink
    October 3, 2017 9:25 pm

    Darwin Cyclone history

    24-25 November 1839
    A severe cyclone wrecked the early British settlement at Port Essington on the Cobourg Peninsula. The Royal Navy sloop Pelorus was driven ashore and half buried in the mud. The barometer fell to 965 hpa as the cyclone centre arrived and a storm surge to about 3 metres above the high water mark occurred.

    6-7 Jan 1897 – “The Great Hurricane”
    Late on 6 January a severe cyclone struck the township of Palmerston (Darwin) reducing most of the buildings to ruins. The pearling fleet in the harbour was decimated and altogether 28 lives were lost. A lowest pressure of 960 hpa was recorded at Charles Point while 296 mm of rain fell on the town overnight. While cyclonic force winds had been recorded in 1878 and 1881, this was the first time Darwin (then called Palmerston) had been virtually destroyed by a cyclone.

    In 1917 and again in 1937 cyclones took lives and caused far-reaching damage in and around Darwin.

    3-11 Mar 1919
    A cyclone formed in the Joseph Bonaparte Gulf near Wyndham where 440 mm of rain fell in 40 hours. The cyclone intensified as it moved northwards passing just west of Charles Point late on 5 March. Moderate damage was caused to the Lightkeeper’s buildings and also in Darwin harbour where two vessels were sunk.

    8-11 Mar 1937
    A severe cyclone moved into Darwin from the northwest causing severe damage throughout the town and the death of one resident. Huge seas ran in the harbour with waves breaking over the cliffs on the foreshore. Winds gusted to 158 km/h.

    29 Nov-3 Dec 1948
    A severe cyclone produced heavy damage on the Tiwi Islands and moderate damage in Darwin. Winds over the Tiwi Islands were estimated at 160 km/h.

    21-25 Dec 1974 – Cyclone Tracy – caused almost total destruction and took 65 lives. Wind gusts 217 kph before anemometer at Darwin Airport failed. 950 hpa. Category 3 (category 4 on the ABC).

    19-25 March 1985 – Cyclone Sandy
    Surges up to three metres were experienced, with turtles and pilot whales being swept ashore. Centre Island weather station recorded a minimum pressure of 973 hpa and a maximum wind gust of 220 km/h. (Source: Bureau of Meteorology)

    Looks like they are due for another one.

  8. Bitter&twisted permalink
    October 4, 2017 7:30 am

    No, No, this graph is all wrong!
    Those nice people, from the Guardian and the BBC, told me hurricanes were getting worse.

  9. CheshireRed permalink
    October 4, 2017 8:31 am

    Paul, the Telegraph are running with that CAT turbulence BS ‘study’ by Dr Paul Williams!

  10. RAH permalink
    October 5, 2017 12:13 pm

    Looks like we Yanks aren’t done with hurricanes yet. What is now Tropical Depression 16 in the extreme western Caribbean is expected to develop and move northward. Joe Bastardi believes it will be a Cat 2 when it comes ashore in the Florida Panhandle well east of the National Hurricane centers current projected track.

    TS development during the 2nd half of the season typically shifts from the MDR in the Atlantic to the West Caribbean or near shore development and so it has this year also.

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