Northern Territory in May 2013: A hot start precedes a wet finish

  • Northwest Top End swelters in the warmest start to May
  • SSTs remain warm off NW coast
  • Late May record rainfalls in western Top End

Hot start to the month

May started exceptionally hot for Territorians, particularly those northwest of the Barkly. Darwin Airport, Pirlangimpi and Point Fawcett (Bathurst Is) each experienced their warmest two week period to the start of May with mean daily maximum temperatures from the 1st to the 14th of 34.1 °C, 34.2 °C and 33.7 °C degrees, respectively. This beat previous respective marks of 34.0 °C at Darwin set in 1987, 33.9 °C at Pirlangimpi set in 1998 and 32.9 °C at Point Fawcett set in 2002.

This initial hot spell also helped Pirlangimpi record its second hottest May on record with an average daily maximum temperature of 33.5 °C over the 31 days. This was the hottest May since 2002 when the mean daily maximum for May was 33.9.

Overall, most stations in the NT were hotter than average for the first half of May. As this time of year marks the transition of wet to dry, it is common for preliminary May days to be hotter than average. These conditions seemed to persist into late May, with the likely causes being warm ocean surface temperatures (see below) coupled with the absence of a cool, dry surge.

Warm SSTs drive AS rainfall

The sea surface temperature (SST) remained very much above average off the northwest coast of Australia during May with some areas nearly two degrees above the long-term average and exceeding the previous May SST temperature record. The temperature of the sea surface is an important weather ‘driver’ for the NT. Warm SSTs along the coast during May can increase the temperature of the afternoon sea breeze, increasing daily maximum temperatures, and also add humidity to the air, thus keeping minimum temperatures warms in coastal regions also.

In addition to temperature, warm SSTs off the northwest coast can provide tropical moisture to cloud bands that sweep across the central part of the continent. This Month the Alice Springs District saw 4 cloud band events providing ample rainfall to the region. Alice Springs Airport measured 42.6 mm this month, this is more than double their long-term average and their wettest May in 9 years. Across the whole Alice Springs District, every site measured above average rainfall with some sites recording their wettest May on record. To the North of Alice Springs, Rabbit Flat (a WMO climate reference station) and The Granites both saw their wettest May on record with 82.0 mm and 93.0 mm respectively. Warm SSTs off the northwest coast was a primary driver of these wet conditions.

Dry season rainfall for Top End

May is a transition month, which means that the air mass over the Top End has to change from warm and humid to cool and dry. The mechanism for change is related to southern winter conditions by the presence of strong high pressure systems. These systems bring cool, dry southeasterly winds from higher latitudes and dry season conditions to the Top End.

In May a southeasterly wind change reached the north coast on the 24th. As the incumbent southeasterlies met the warm humid airmass over the Top End, a series of showers were triggered which broke several rainfall records for May (see below). Showers are always a possibility ahead of a southeasterly wind change as the cold dry air undercuts the warm humid air and lifts it to form cloud. What made this event distinct was the depth of moisture in the atmosphere. The warm SSTs off the northwest coast, coupled with prevailing easterly winds during the early half of May contributed to a deep layer of moisture and a good environment for showers on the 24th.

Rainfall

Most of the NT saw above average rainfall in May except for the Victoria River District that was near average for the month. The four northwest cloudband events mentioned above contributed to the very much above average rainfall in the Alice Springs District. It was from these events that The Granites and Rabbit Flat, a WMO climate reference station, accumulated their highest total May rainfall on record. In the Top End, heavy rain fell on the 24th as a surge of dry air contracted to the north, as described above. It is unusual for a location in the western Top End to measure more than 100 mm in a dry season month, it is even more unusual for over 100 mm to fall in one day. From the rainfall event on the 24th several sites saw their highest May daily rainfall on record including Batchelor Aero with 101.4 mm on the 24th. When averaged across the Territory, including the above average rainfall in both the north and the south, the mean monthly rainfall for May was 34.5 mm which is 21.00 mm (155.2%) above the long-term average (average = 13.53 mm)

The wettest overall was Litchfield with 167.0 mm, followed by Batchelor Aero with 150.0 mm, and then North East Island with 144.4 mm. The wettest single day was at Batchelor Aero with 101.4 mm on the 24th, followed by North East Island with 94.0 mm on the 19th, and then Southport with 91.6 mm on the 24th.

Temperature

Both mean daily maximum and mean daily minimum temperatures were above average for May. When combined into a single mean daily temperature the NT say the warmest May since 2007 with a mean NT temperature of 23.22 °C, which is 1.4 °C warmer than the average. The warmest mean temperature on average was at Cape Don with 29.4 °C, followed by Jabiru Airport with 29.1 °C, and then Oenpelli Airport with 29.0 °C. The coolest on average was Arltunga with 17.4 °C, followed by Alice Springs Airport with 17.5 °C, followed by Yulara Aero with 18.0 °C.

Maximum temperature

Warm maximum temperatures dominated the NT for most of the month. When averaged across the NT, the monthly mean maximum temperature was 29.0 °C, which is 0.9 °C above the average. Around 20 May, a cool surge of dry air began to shift north, reaching the north coast on the 24th. This cooled the daily maximum temperatures significantly for a few days before the temperature began to creep up again. When averaged across the whole month the cool temperatures at the end of the month were not enough to lower the monthly average below the long-term mean but several places that were on track to record their warmest May on record saw cool enough temperatures to avert such records. As such, Point Fawcett was the only site to set a new highest May mean daily maximum temperature on record this month. Earlier in the month, on the 2nd and 3rd, there were several sites that had their highest May temperature on record including Dum-In-Mirrie and Channel Point.

The hottest temperatures recorded in the NT this months was at Victoria River Downs with 37.7 °C on the 3rd, followed by Bradshaw which saw 37.6 °C on the 2nd, 3rd, and 4th, and then Douglas River with 37.5 °C on the 3rd, and Bradshaw also with 37.5 °C on the 6th.

The coldest daily maximum temperatures around the NT all occurred on 15 May. These were at Yuendumu with 13.5 °C, followed by Walungurru with 14.1 °C (which was also their coldest May day on record), and then Territory Grape Farm with 14.2 °C.

The warmest days on average were at Bradshaw with 35.0 °C, followed by Noonamah with 34.7 °C, and then Douglas River with 34.6 °C. The coolest days on average were at Kulgera with 23.9 °C, followed by Arltunga with 24.0 °C, and then Alice Springs Airport with 24.8 °C.

Minimum temperature

Minimum temperatures in May followed a similar pattern to the maximum temperatures. They stayed much warmer than average, especially across the Top End, until the dry surge arrived. The Territory average mean daily minimum temperature for way was 17.5 °C, which is 1.9 °C above normal for May. Several sites, including MacArthur River Mine and Kulgera, had their warmest May night (highest daily minimum temperature) on record. Only two sites, Kulgera and Ngayawili, had their highest May mean daily minimum temperature on record.

Around the NT, the warmest nights on average were at Cape Don with 26.2 °C, followed by McCluer Island with 25.9 °C, and then Cape Wessel and North East Island with 25.8 °C. The warmest night was recorded at Cape Don with 28.2 °C on the 3rd, followed by North East Island with 28.1 °C on the 2nd, and then McCluer Island with 27.8 °C on the 7th.

The coldest nights were at Alice Springs Airport with 2.6 °C on the 27th and 3.0 °C on the 26th, this was followed by Yulara Aero with 3.3 °C on the 16th. The coolest nights on average were at Alice Springs Airport with 10.3 °C, followed by Arltunga with 10.7 °C, and then Yulara Aero with 10.9 °C.

Wind

The strongest wind gust was at Cape Wessel with 78 km/h on the 3rd, followed by McCluer Island with 72 km/h on the 4th and Centre Island also with 72 km/h on the 25th.

Further information

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Extremes in May 2013
Hottest day 37.7 °C at Victoria River Downs on the 3rd
Warmest days on average 35.0 °C at Bradshaw
Coolest days on average 23.9 °C at Kulgera
Coldest day 13.5 °C at Yuendumu on the 15th
Coldest night 2.6 °C at Alice Springs Airport on the 27th
Coolest nights on average 10.3 °C at Alice Springs Airport
Warmest nights on average 26.2 °C at Cape Don
Warmest night 28.2 °C at Cape Don on the 3rd
Warmest on average overall 29.4 °C at Cape Don
Coolest on average overall 17.4 °C at Arltunga
Wettest overall 167.0 mm at Litchfield
Wettest day 101.4 mm at Batchelor Aero on the 24th
Highest wind gust 78 km/h at Cape Wessel on the 3rd

Maps
ObservedAnomalyDecile rank
Total
rainfall
Map of Rainfall totals Map of Percentage of normal rainfall Map of Rainfall deciles
Mean
daily
maximum
temperatures
Map of Mean maximum temperature Map of Anomaly in mean maximum temperature Map of Decile rank of mean maximum temperature
Mean
daily
minimum
temperatures
Map of Mean minimum temperature Map of Anomaly in mean minimum temperature Map of Decile rank of mean minimum temperature

Click on a map to show it full size in a pop-up window


Record highest May daily rainfall
Highest daily rainfall
in May 2013 (mm)
Previous wettest
for May
Years of
record
Curtin Springs 60.6 on the 21st 57.2 on the 25th in 1979 59
Litchfield 55.4 on the 24th 38.4 on the 28th in 2010 27
Yulara Aero 42.4 on the 21st 41.4 on the 18th in 2004 23
Batchelor Aero 101.4 on the 24th 57.6 on the 19th in 2007 19
Glen Helen Lodge 38.0 on the 12th 31.6 on the 20th in 1990 18
Point Fawcett 61.0 on the 23rd 58.0 on the 13th in 1998 18
Wandie Creek 64.6 on the 18th 34.0 on the 7th in 1990 17
Groote Eylandt Airport 61.8 on the 10th 41.0 on the 19th in 2004 15
Wongalara 48.4 on the 24th 11.0 on the 24th in 2012 13
Darwin River Ridge 67.4 on the 24th 61.6 on the 23rd in 2010 12
Middle Point 44.6 on the 24th 41.2 on the 20th in 2004 12
Adelaide River West 38.5 on the 23rd 24.5 on the 28th in 2004 10
Foelsche Headland 15.0 on the 23rd 10.6 on the 6th in 2004 10
Maningrida Aero 39.4 on the 6th 27.0 on the 25th in 2012 10



Record highest total May rainfall
Total rainfall
for May 2013 (mm)
Previous wettest
for May
Years of
record
Average for
May
Litchfield 167.0 99.2 in 2010 27 17.8
The Granites 93.0 60.4 in 2004 24 15.5
Batchelor Aero 150.0 67.8 in 2007 19 24.6
Rabbit Flat 82.0 60.8 in 2010 17 15.2
Wongalara 48.4 15.0 in 2012 13 5.3
Maningrida Aero 83.8 54.2 in 2004 10 26.6



Record highest May temperature
Highest temperature
in May 2013 (°C)
Previous warmest
for May
Years of
record
Average for
May
Channel Point 35.2 on the 3rd 35.0 on the 10th in 1996 19 31.0
Dum In Mirrie 36.9 on the 3rd 36.0 on the 1st in 2003 15 32.0
Point Fawcett 35.4 on the 16th 34.0 on the 22nd in 2003 15 31.2
Middle Point 37.3 on the 3rd 36.0 on the 25th in 2003 12 33.2
Walungurru 34.9 on the 4th 34.2 on the 1st in 2007 12 27.4



Record lowest May daily maximum temperature
Lowest daily maximum
temperature
in May 2013 (°C)
Previous coolest
for May
Years of
record
Average for
May
Walungurru 14.1 on the 15th 16.0 on the 29th in 2004 12 27.4



Record highest May mean daily maximum temperature
Mean daily maximum
temperature
for May 2013 (°C)
Previous warmest
for May
Years of
record
Average for
May
Point Fawcett 32.9 32.2 in 2002 14 31.2



Record highest May daily minimum temperature
Highest daily minimum
temperature
in May 2013 (°C)
Previous warmest
for May
Years of
record
Average for
May
McArthur River Mine 25.0 on the 22nd 24.6 on the 3rd in 2010 36 16.4
Kulgera 20.4 on the 5th 19.6 on the 2nd in 1993 32 8.9
McCluer Island 27.8 on the 7th 27.5 on the 27th in 2004 14 24.9
Ngayawili 25.8 on the 17th 25.4 on the 16th in 2010 14 22.1
Walungurru 23.4 on the 11th 23.0 on the 10th in 2002 12 15.4



Record highest May mean daily minimum temperature
Mean daily minimum
temperature
for May 2013 (°C)
Previous warmest
for May
Years of
record
Average for
May
Kulgera 12.9 11.7 in 1992 31 8.9
Ngayawili 23.9 = 23.9 in 2010 13 22.1



Summary statistics for May 2013
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2013
Diff
from
average
Highest for
May
2013
Mean for
May
2013
Diff
from
average
Lowest for
May
2013
Total for
May
2013
Average
for
May
Rank of
May
2013
Fraction of
May
average
Darwin-Daly (district 14GA)
Batchelor Aero 33.1 +0.4 35.7 3rd 21.0 +2.2 15.6 26th 150.0 24.6 highest 610%
Black Point 31.6 +0.4 33.2 2nd 24.9 +1.3 20.9 25th 4.2 36.5 average 12%
Bradshaw 35.0 +1.8 37.6 4th 21.4 +3.4 11.9 26th 0.6 19.0 high 3%
Cape Don 32.6   34.9 6th 26.2   23.2 25th 19.8 32.2 average 61%
Central Arnhem Plateau 31.2   33.9 3rd 20.9   13.7 25th 49.2
Croker Island Airport 31.2   32.8 3rd 24.8   20.8 25th 16.2
Darwin Airport 32.7 +0.7 35.2 2nd 23.7 +1.6 17.9 25th 31.6 21.3 high 148%
Darwin NTC 31.7   34.6 5th 25.2   20.0 25th
Delamere Weapons Range 32.3 +1.0 35.8 3rd 19.6 +1.9 13.8 26th 0 5.7 lowest 0%
Douglas River 34.6 +1.6 37.5 3rd 19.7 +3.3 12.1 25th 6.0 10.4 high 58%
Dum In Mirrie 32.9 +0.9 36.9 3rd 23.7 +1.9 18.9 25th 46.2 15.6 high 296%
Jabiru Airport 34.3 +0.8 36.8 2nd 24.0 +2.2 18.5 25th 44.0 12.6 high 349%
Katherine Country Club 33.5   35.9 3rd 20.1   10.9 26th 0
Mango Farm 33.4 +0.5 36.2 3rd 20.6 +2.1 14.1 26th 28.0 9.3 high 301%
McCluer Island 29.8 +0.5 31.4 1st 25.9 +1.0 22.7 25th 129.2 49.1 high 263%
Middle Point 34.2 +1.0 37.3 3rd 21.2 +2.2 14.8 25th 70.4 20.2 high 349%
Murganella Airstrip 32.2   34.1 16th 22.6   16.6 25th 20.8
Noonamah 34.7   37.2 3rd 21.3   15.4 26th 13.0
Oenpelli Airport 34.3   36.7 2nd 23.7   16.8 25th 23.4
Pirlangimpi 33.5 +1.1 35.5 2nd 23.4 +2.1 20.3 25th 8.0 21.9 average 37%
Point Fawcett 32.9 +1.7 35.4 16th 22.6 +1.4 17.1 26th 110.4 35.5 high 311%
Point Stuart 32.0   34.0 3rd 23.2   16.5 25th 29.0 14.5 average 200%
Tindal RAAF 33.1 +1.1 36.0 3rd 19.4 +2.0 10.7 26th 0 1.4 lowest 0%
Arnhem (district 14BC)
Cape Wessel 30.6   32.8 1st 25.8   23.2 30th
Gove Airport 30.5 +0.7 32.1 2nd 23.9 +1.3 21.3 29th 86.6 89.6 average 97%
Groote Eylandt Airport 31.3 +0.4 34.2 2nd 21.4 +2.7 14.4 25th 69.6 28.5 high 244%
Maningrida Aero 31.9   34.4 2nd 23.0   16.8 25th 83.8 26.6 highest 315%
Milingimbi 31.9   33.6 2nd 23.7   17.8 25th 50.0 33.3 high 150%
Ngayawili 31.5 +0.6 33.1 18th 23.9 +1.8 20.1 25th 10.8 31.6 average 34%
North East Island 30.8   32.9 1st 25.8   23.0 25th 144.4 49.1 high 294%
Warruwi 30.9 +0.2 32.4 23rd 25.0 +1.0 20.8 25th 48.2 15.0 v high 321%
Roper-Mcarthur (district 14DE)
Borroloola 32.5 +0.4 35.5 2nd 17.5 +1.9 7.9 26th 23.0 5.7 v high 404%
Centre Island 29.8 +0.4 33.1 1st 23.5 +1.0 18.1 25th
Daly Waters 33.0 +2.0 36.8 2nd 17.4 +1.4 10.4 26th 0.2 7.2 average 3%
McArthur River Mine 33.1 +0.9 36.7 2nd 19.6 +3.2 10.0 27th 1.0 7.6 average 13%
Ngukurr 32.7   35.8 22nd 20.7   10.9 25th 10.2
Wollogorang 32.3 +1.0 35.9 1st 17.5 +1.6 8.2 27th 6.9 8.2 high 84%
Victoria (district 14F)
Timber Creek 33.7 +0.8 36.9 2nd 19.6 +1.4 13.5 27th 2.4 7.8 high 31%
Victoria River Downs 33.7 +1.9 37.7 3rd 18.6 +2.8 9.9 27th 0 6.0 lowest 0%
Wave Hill 32.4 +1.3 37.0 6th 17.8 +2.8 10.7 28th 2.8 8.6 average 33%
Barkly (district 15A)
Brunette Downs 30.2 +0.4 35.7 4th 16.7 +1.7 8.9 26th 16.0 8.1 high 198%
Tennant Creek Airport 28.3 +0.8 34.3 21st 17.3 +1.0 10.9 24th 20.8 8.5 high 245%
Alice Springs (district 15B)
Alice Springs Airport 24.8 +1.8 32.2 6th 10.3 +2.1 2.6 27th 42.6 18.9 high 225%
Arltunga 24.0 +1.1 30.8 5th 10.7 +2.9 5.6 17th 44.8 20.1 high 223%
Curtin Springs 25.1 +1.4 33.3 4th 11.4 +2.8 4.3 16th 68.6 17.8 v high 385%
Jervois 26.3 +1.0 32.8 3rd 12.6 +2.7 7.7 28th 60.4 18.5 v high 326%
Kulgera 23.9 +1.3 31.8 4th 12.9 +4.0 4.2 26th 64.4 12.3 v high 524%
Rabbit Flat 28.6 +0.4 36.1 3rd 14.0 +2.4 7.7 27th 82.0 15.2 highest 539%
Territory Grape Farm 26.0 +0.7 32.9 4th 12.4 +3.2 4.7 27th 36.4 24.1 high 151%
Walungurru 26.6 -0.8 34.9 4th 16.3 +0.9 10.2 16th 38.0 17.4 high 218%
Yulara Aero 25.2 +1.0 33.0 4th 10.9 +1.7 3.3 16th 48.0 13.0 high 369%

Notes

A Monthly 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 12 pm on Monday 3 June 2013. 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 all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record, 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.

The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.

Further information

Media
(03) 9669 4057
Enquiries