Northern Territory Wet Season 2010-11: One for the record books

With a strong La Niña enhancing Northern Territory rainfall, and the added precipitation from Tropical Cyclone Carlos, the 2010/2011 wet season is one for the record books. Many rainfall records were broken across the Territory as well as several temperature records.

Three stations exceed 3 metres of rain

Prior to this year, only one station has ever surpassed the three-metre mark during a wet season, anywhere in the Northern Territory - when Pirlangimpi recorded 3048.6mm during the 1998/99 wet season. We now have three extra stations in this category, including a new NT wet season rainfall record. The three-metre club includes Karama* with 3016.2 mm, Wagait Beach with 3142.4 mm and Leanyer* is the new NT record holder with 3165.1 mm. On 16 February the rain gauges at Karama* and Leanyer* overflowed due to the extreme nature of the rainfall during Carlos. Consequently, these rainfall totals will be an underestimate of the true amount.

Darwin Airport breaks multiple rainfall records

In the 24 hour period to 9 am on 16 February, Darwin Airport recorded 367.6 mm of rain. The previous highest 24 hour rainfall for Darwin Airport was recorded on the 3rd of January 1997, when Tropical Cyclone Rachel brought 290.4 mm of rain. The 3-day total (15 to 17 February 2011) was 684.8 mm, breaking the previous 3-day record set between 8 and 10 December 1998, when Tropical Cyclone Thelma brought 462.0 mm of rain (see Special Climate Statement 29). The monthly rainfall total for February at Darwin Airport was 1110.2 mm, becoming the wettest of any month on record, passing the March 1977 total of 1013.6 mm.

On the morning of 4 March the rain gauge reading was only 15.4 mm, but this was enough to bring the wet season total to 2511.2 mm and passing the wet season record of 2499.4 mm set in the 1997/1998 wet season. By the end of the wet season Darwin Airport had received 2918.4 mm of rainfall in 147 rain days.

Strong La Niña enhances rainfall

Historically, La Niña brings above average rainfall to Northern Australia and this year has been no exception. This years La Niña episode in tropical Pacific Ocean has compared with 1998 and 1974 in both strength and influence on the Top End weather. The most notable aspect of this La Niña has been a very strong atmospheric component. Southern Oscillation Index (SOI) values have been at record highs for most of this wet season, which corresponds with low pressure anomalies and enhanced thunderstorm activity over Darwin. The moderate to strong oceanic component of this La Nina event produced warmer than normal sea surface temperatures (SSTs) around Northern Australia, which also enhanced rainfall in the region. From October through April, La Niña was the strongest contributor to this season’s large rainfall total.

TC Carlos forms over Darwin

TC Carlos formed over the Beagle Gulf early on 16 February and moved very slowly southeast over Darwin and surrounding rural area. This contributed further rainfall to the already wet condititons. TC Carlos was downgraded to a tropical low at 6:30 am CST on 17 February, near Batchelor. Ex-TC Carlos then tracked southwards over the western Top End reaching the WA/NT border on 19 February. Very heavy rainfall associated with TC Carlos broke many rainfall records in the region. The heavy rain had a major impact on Darwin and surrounding areas, causing widespread flooding of low lying areas, inundating many houses and damaging roads and properties. Flooding of coastal areas was exacerbated by some of the largest astronomical tides of the year.

Squally winds with gusts reaching 98 km/h lashed the Darwin area during the night of the 15th and again on the 16th, felling trees, cutting roads, power lines and damaging properties. Most government departments, schools and businesses were closed for two days during the event. Darwin Airport was also closed during the worst weather conditions on 16 February. Ex-TC Carlos caused widespread flooding elsewhere in the Darwin-Daly District, including a major flood in the Daly River, inundating the community of Nauiyu about 150 km south of Darwin.

Rainfall

With nearly 472 mm above the wet season average, this wet season ranked 3rd wettest for the Northern Territory. Nearly every rainfall recording station in the NT measured either very much above average or highest on record this wet season. Some sites, including Darwin Airport, Adelaide River Post Office, Litchfield and Yirrkala Tropical Gardens, had their highest total October to April rainfall on record. Gove Airport, Tennant Creek Airport, Port Keats Aero, Jabiru Airport, and the Katherine Aviation Museum all measured their 2nd wettest wet season on record.

The wettest overall was Leanyer* with 3165.1 mm, followed by Wagait Beach with 3142.4 mm, followed by Karama* with 3016.2 mm. The driest overall was Curtin Springs with 244.7 mm. The wettest single day was at Darwin Airport with 367.6 mm on 16 Feb 2011.

Maximum temperature

The average daily maximum temperature for the NT during the 2010/2011 wet season was 33.0 C. This is 2.01 C below the wet season normal and ranks as the 3rd coolest wet season on record behind the 1973/1974 and 1975/1976 wet seasons. Batchelor Aero and Bradshaw are the only locations that had their coldest October to April day (lowest daily maximum temperature) on record. Seventeen sites had their lowest October to April mean daily maximum temperature on record, including the Katherine Aviation Museum and the Tindal RAAF which both had a mean daily maximum temperature of 33.6 C. The mean daily maximum temperature at Darwin Airport from October 2010 to April 2011 was 31.8 C, which is the lowest for this period since the 1956/57 wet season when the mean daily maximum temperature was 31.7 C (the average for this period is 32.4 C).

Even with the low average daily maximum temperature for the season, some high temperature records were broken. For Example, on 27 January, Yulara broke its highest temperature record when it reached a daytime maximum temperature of 46.3 °C, only to break this record again the following day with 46.4 °C. This new record falls just 1.9 °C shy of the Northern Territory maximum temperature record. Yulara recorded its hottest month on record in January with an average maximum temperature of 40.9 °C, which surpasses the previous record of 40.8 °C set in February 2007. Furthermore, Yulara measured 17 consecutive days above 40 °C during January, including 11 consecutive days above 42 °C which are both record longest hot spells of that magnitude for the site. The dates of this hot spell were from the 14 January to the 30 January, inclusive.

The hottest days in the NT were at Yulara Aero as mentioned above, followed by Walungurru with 46.2 °C on 28 Jan 2011. The coldest days in the NT were all on 15 Oct 2010 when the maximum temperature at Kulgera reached only 16.6 °C , at Arltunga the daily maximum was 17.2 °C and Alice Springs Airport had 17.6 °C. Kulgera had another cold day with 17.6 °C on 16 Oct 2010.

The warmest days on average were at Rabbit Flat with 35.3 °C, followed by McArthur River Mine and Timber Creek with 34.7 °C, and then Kidman Springs with 34.5 °C. The coolest days on average were at Arltunga with 30.2 °C, followed by Alice Springs Airport with 31.0 °C, followed by Channel Point, Gove Airport and Point Fawcett, all with 31.4 °C.

 

Minimum temperature

The average daily minimum temperatures around the Territory for the wet season were near average to slightly above average across the Top End, and below average to very much below average across the Alice Springs District. The average daily minimum temperature for the NT this wet season was 22.1 C which is 1.0 C below normal.

The coldest nights were recorded at Arltunga with 2.0 °C on 12 Apr 2011, followed by 3.8 °C on 25 Apr 2011, and then 4.4 °C on 19 Apr 2011. It is no surprise then that the coolest nights on average durring the wet season were at Arltunga with 16.1 °C. The next coolest nights were at Alice Springs Airport with 16.6 °C followed by Kulgera with 17.2 °C.

The warmest night was recorded at Papunya with 31.6 °C on 28 Jan 2011, followed by Walungurru with 30.9 °C also on 28 Jan 2011. The warmest nights on average were at Centre Island with 25.7 °C, followed by Warruwi with 25.3 °C.

Lajamanu and Borroloola both tied their lowest October to April mean daily minimum temperature on record with 21.4 °C and 22.8 °C respectively. Darwin Airport with 24.3 °C and Tennant Creek Airport with 21.8 °C both recorded their lowest October to April mean daily minimum temperature since 1975.

Wind

The strongest wind gust was at Daly Waters with 98 km/h on 16 Nov 2010. Darwin Airport also experienced a wind gust of 98 km/h on 15 Feb 2011 associated with pre-TC Carlos. The next highest gusts were at Walungurru with 96 km/h on 28 Jan 2011, followed by North East Island with 94 km/h on 21 Jan 2011.

Madden-Julian Oscillation

The Madden-Julian Oscillation (MJO) played a surprisingly minor role in this wet season's rainfall. The pattern of the oscillation was somewhat broken and erratic, and even when the MJO showed signs of a strong burst its effects were seemingly dwarfed by the strong La Nina.

Further information

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Extremes in October to April 2010-11
Hottest day 46.4 °C at Yulara Aero on 28 Jan 2011
Warmest days on average 35.3 °C at Rabbit Flat
Coolest days on average 30.3 °C at Arltunga
Coldest day 16.6 °C at Kulgera on 15 Oct 2010
Coldest night 2.0 °C at Arltunga on 12 Apr 2011
Coolest nights on average 16.1 °C at Arltunga
Warmest nights on average 25.7 °C at Centre Island
Warmest night 31.6 °C at Papunya on 28 Jan 2011
Warmest on average overall 29.3 °C at Ngukurr
Coolest on average overall 23.2 °C at Arltunga
Wettest overall 3165.1 mm at Leanyer*
Driest overall 244.7 mm at Curtin Springs
Wettest day 367.6 mm at Darwin Airport on 16 Feb 2011
Highest wind gust 98 km/h at Daly Waters on 16 Nov 2010
98 km/h at Darwin Airport on 15 Feb 2011

* Rain gauge overflowed on 16 February


Record highest October to April daily rainfall
Highest daily rainfall
in October to April 2010-11 (mm)
Previous wettest
for October to April
Years of
record
Darwin Airport 367.6 on 16 Feb 2011 290.4 on 3 Jan 1997 69
The Garden 134.6 on 8 Mar 2011 134.4 on 29 Jan 1974 54
Channel Island 311.2 on 16 Feb 2011 290.2 on 13 Dec 2009 27
Atula 119.6 on 22 Feb 2011 119.2 on 28 Feb 2010 30
Mango Farm 230.2 on 18 Feb 2011 218.4 on 14 Apr 1985 26
Nightcliff Sports Club 280.0 on 16 Feb 2011 259.8 on 16 Mar 1977 24
Palmerston 300.0 on 16 Feb 2011 295.7 on 3 Jan 1997 29
Stokes Hill 288.4 on 16 Feb 2011 273.6 on 13 Dec 2009 27
Wagait Beach 367.0 on 16 Feb 2011 279.2 on 3 Mar 2007 15
Leanyer* 344.2 on 16 Feb 2011 271.4 on 3 Jan 1997 19
Territory Wildlife Park 327.0 on 17 Feb 2011 260.0 on 10 Dec 1998 15



Record highest total October to April rainfall
Total rainfall
for October to April 2010-11 (mm)
Previous wettest
for October to April
Years of
record
Average for
October to April
Rosewood 1303.9 1212.6 in 1906/1907 102 617.8
Oenpelli 2003.8 1998.8 in 1975/1976 91 1390.3
Darwin Airport 2926.8 2499.4 in 1997/1998 69 1666.2
Arltunga 713.6 709.5 in 1920/1921 62 234.0
Helen Springs 1034.9 846.6 in 1973/1974 56 401.7
Darwin Botanic Gardens* 2602.0 2419.0 in 1998/1999 48 1680.7
Adelaide River Post Office 2359.0 1926.0 in 2005/2005 34 1427.5
Warramunga 990.9 915.4 in 2000/2001 37 404.0
Darwin River Dam 2688.2 2231.6 in 1998/1999 35 1563.6
Mango Farm 2519.4 1803.7 in 2005/2006 26 1375.8
Channel Island 2945.3 2639.0 in 1996/1997 26 1612.0
Keep River Rangers 1417.3 1213.5 in 1988/1989 23 809.3
Stokes Hill 2522.2 1956.3 in 1976/1977 14 1422.1
Karama* 3016.2 2336.5 in 1998/1999 18 1723.1
Leanyer* 3165.1 2441.2 in 1996/1997 16 1841.8
Northlakes* 2977.5 2600.0 in 1996/1997 13 1835.5
Litchfield 2658.6 2075.1 in 1980/1981 16 1514.9
Elizabeth Valley 2715.6 2309.6 in 1996/1997 14 1654.0
Yirrkala Tropical Gardens 2228.0 1680.4 in 1999/2000 11 1164.7
CSIRO Berrimah 2886.3 2528.6 in 1994/1995 10 2005.1
Pine Creek Council 2036.6 1833.2 in 2005/2006 10 1440.8
Wagait Beach 3142.4 2324.6 in 1997/1998 10 1784.3

* Rain gauge overflowed on 16 February





Record lowest October to April daily maximum temperature
Lowest daily maximum
temperature
in October to April 2010-11 (°C)
Previous coolest
for October to April
Years of
record
Average for
October to April
Batchelor Aero 23.9 on 16 Feb 2011 24.8 on 4 Mar 2007 11 34.2



Record lowest October to April mean daily maximum temperature
Mean daily maximum
temperature
for October to April 2010-11 (°C)
Previous coolest
for October to April
Years of
record
Average for
October to April
Brunette Downs 33.7 33.9 in 2000/2001 38 36.5
Victoria River Downs 34.1 34.8 in 2000/2001 34 36.5
Daly Waters AWS 33.7 34.2 in 2000/2001 38 36.0
Timber Creek 34.7 35.5 in 2000/2001 29 36.6
McArthur River Mine 34.6 35.2 in 1978/1979 17 36.6
Wollogorang 33.7 34.1 in 1976/1977 21 35.6
Katherine Aviation Museum 33.6 34.5 in 2000/2001 23 35.5
Tindal RAAF 33.6 33.9 in 2000/2001 19 35.1
Douglas River 33.4 34.0 in 20052006 13 35.0
Lajamanu 34.2 = 34.2 in 1973/1974 14 36.5
Ngukurr 34.4 35.3 in 1964/1965 10 36.2
Delamere Weapons Range 33.4 34.0 in 1998/1999 12 35.5
Kidman Springs 34.5 35.6 in 1999/2000 11 36.8
Batchelor Aero 32.5 33.1 in 1999/2000 11 34.2
Pine Creek Council 32.7 33.6 in 2000/2001 10 34.5




Record lowest October to April mean daily minimum temperature
Mean daily minimum
temperature
for October to April 2010-11 (°C)
Previous coolest
for October to April
Years of
record
Average for
October to April
Borroloola 22.8 = 22.8 in 2006/2007 12 23.4
Lajamanu 21.4 = 21.4 in 2000/2001 13 22.2
Dum In Mirrie 25.0 = 25.0 in 2007/2008 11 25.5
Pine Creek Council 23.2 = 23.2 in 2007/2008 10 23.7



Summary statistics for October to April 2010-11
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean Diff
from
average
Highest Mean Diff
from
average
Lowest Total Average
Rank Fraction of

average
Darwin-Daly (district 14GA)
Batchelor Aero 32.5 -1.7 38.3 2 Oct 2010 23.4 0.0 15.1 20 Apr 2011 2355.6 1511.3 highest 156%
Channel Point 31.4 -0.7 34.5 30 Nov 2010 24.3 -0.3 18.4 20 Apr 2011 2141.2 1759.7 high 122%
Darwin Airport 31.8 -0.6 36.5 24 Oct 2010 24.3 -0.5 19.1 21 Apr 2011 2926.8 1666.2 highest 176%
Delamere Weapons Range 33.4 -2.1 40.0 4 Oct 2010 23.2 -0.4 16.9 29 Apr 2011 1346.4 861.8 high 156%
Douglas River 33.4 -1.6 39.7 4 Oct 2010 23.0 0.0 13.9 20 Apr 2011
Dum In Mirrie 31.7 -0.5 36.5 2 Oct 2010 25.0 -0.5 19.3 20 Apr 2011 2231.8 1755.7 v high 127%
Jabiru Airport 33.7 -1.2 38.9 4 Oct 2010 24.3 -0.1 19.7 28 Apr 2011 2422.6 1505.2 v high 161%
Katherine Aviation Museum 33.6 -1.9 39.2 6 Dec 2010 23.1 -0.5 13.7 20 Apr 2011 1651.9 1102.7 v high 150%
Middle Point 33.4   38.1 3 Oct 2010 23.4   16.3 20 Apr 2011 2286.0
Noonamah 33.4   38.1 4 Oct 2010 23.5   16.9 20 Apr 2011 2667.4
Pine Creek Council 32.7 -1.8 38.5 4 Oct 2010 23.2 -0.5 17.2 19 Apr 2011 2036.6 1440.8 highest 141%
Point Fawcett 31.4 -0.8 33.9 8 Dec 2010 24.4 -0.6 16.5 21 Apr 2011 2894.4 1431.7 highest 202%
Port Keats Aero 32.6 -1.0 38.0 2 Oct 2010 24.1 -0.4 15.3 20 Apr 2011 1956.8 1062.4 v high 184%
Tindal RAAF 33.6 -1.5 39.3 6 Dec 2010 23.2 -0.5 14.3 20 Apr 2011 1264.0 1064.3 high 119%
Arnhem (district 14BC)
Gove Airport 31.4 -0.5 34.6 1 Dec 2010 23.9 +0.2 20.3 19 Apr 2011 2135.8 1286.4 v high 166%
Groote Eylandt Airport 32.5 -0.9 36.1 5 Dec 2010 23.6 +0.1 16.1 19 Apr 2011 1553.4 1354.2 high 115%
Maningrida Aero 32.0   36.4 6 Nov 2010 24.2   20.7 3 Nov 2010 2489.0
Ngayawili 31.8 -0.3 35.6 1 Dec 2010 24.7 +0.1 21.0 5 Nov 2010 1546.4 1514.0 average 102%
Warruwi 31.8 -0.4 35.4 6 Dec 2010 25.3 -0.3 22.2 16 Feb 2011 1576.6 1125.5 v high 140%
Roper-Mcarthur (district 14DE)
Borroloola 33.9 -1.2 40.5 5 Dec 2010 22.8 -0.6 13.5 19 Apr 2011 1375.4 908.8 high 151%
Bulman 33.7   40.2 5 Dec 2010 23.2   15.6 19 Apr 2011 1807.4
Centre Island 32.4 -1.0 37.4 14 Dec 2010 25.7 -0.6 21.8 16 Oct 2010 1839.4 1006.7 v high 183%
Daly Waters 33.7 -2.3 40.1 25 Oct 2010 21.9 -0.9 11.7 20 Apr 2011 1132.8 636.5 v high 178%
Larrimah 33.8 -1.9 40.1 25 Nov 2010 22.4 -0.7 12.0 19 Apr 2011 1319.6 837.8 v high 158%
McArthur River Mine 34.6 -2.0 40.7 5 Dec 2010 23.4 0.0 14.9 19 Apr 2011 1462.2 727.0 v high 201%
Ngukurr 34.4 -1.8 40.9 5 Dec 2010 24.1 0.0 17.2 19 Apr 2011 1395.0 744.6 v high 187%
Wollogorang 33.7 -1.9 39.4 25 Oct 2010 22.3 -0.3 12.3 17 Oct 2010 1111.3 934.3 average 119%
Victoria (district 14F)
Kidman Springs 34.5 -2.3 41.6 24 Nov 2010 23.5 -0.4 12.4 19 Apr 2011 981.6 731.9 high 134%
Lajamanu 34.2 -2.3 42.6 30 Jan 2011 21.4 -0.8 9.7 19 Apr 2011 927.8 474.8 v high 195%
Timber Creek 34.7 -1.9 41.5 24 Nov 2010 23.7 -0.5 13.8 19 Apr 2011 1499.1 943.9 v high 159%
Victoria River Downs 34.1 -2.4 40.9 4 Oct 2010 22.9 -0.6 11.9 19 Apr 2011 1164.5 636.0 v high 183%
Barkly (district 15A)
Brunette Downs 33.7 -2.8 41.0 15 Dec 2010 21.9 -0.8 11.1 16 Oct 2010 808.4 389.2 v high 208%
Tennant Creek Airport 32.8 -2.5 41.1 27 Jan 2011 21.8 -1.6 12.2 16 Oct 2010 843.6 431.5 v high 196%
Alice Springs (district 15B)
Alice Springs Airport 31.0 -2.2 43.0 27 Jan 2011 16.6 -1.3 4.7 1 Nov 2010 492.0 215.9 v high 228%
Arltunga 30.3   40.2 27 Jan 2011 16.1   2.0 12 Apr 2011 713.6 234.0 highest 305%
Curtin Springs 33.1 -1.1 45.5 28 Jan 2011 18.1 -0.2 6.0 16 Oct 2010 244.7 166.9 high 147%
Kulgera 31.4 -1.6 44.9 28 Jan 2011 17.3 -1.1 4.5 11 Apr 2011 337.6 192.0 high 176%
Rabbit Flat 35.3 -2.0 44.1 30 Jan 2011 20.7 -0.8 9.2 24 Apr 2011 719.2 442.6 high 162%
Territory Grape Farm 32.6 -2.1 43.5 27 Jan 2011 17.5 -1.6 6.6 16 Oct 2010 430.4 235.3 v high 183%
Yulara Aero 33.2 -1.5 46.4 28 Jan 2011 18.5 -0.4 6.9 16 Oct 2010 391.8 208.6 high 188%
Offshore Islands (district 200)
Northern Endeavour 32.8   36.0 11 Jan 2011 27.5   22.0 27 Dec 2010


Notes

A Seasonal Climate Summary is prepared to list the main features of the weather in Northern Territory using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 2 pm on Wednesday 27 April 2011. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages are long-term means based on observations from the years 1800 to 2009. They are not shown for sites with less than 10 years of record in that time, as they cannot then be calculated reliably.
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Further information

Media
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