Tasmania in May 2011: less rain, lower temperatures

May 2011 was the first month this year without extremely heavy rainfall. The state was mostly drier than usual though cold fronts brought some rain and snow on several days. It was cool overall following many cold and frosty nights and cool days.

  • Cold outbreak with snow and large waves
  • Launceston's coldest May day on record
  • Drier than usual

End to the wet

Cold fronts brought rain to Tasmania on several days during May but it was still drier than usual overall. It was the first month of 2011 without extremely heavy rain, the highest daily total being just 38.6 mm at Lake St Clair on the 14th. Memana (22.6 mm) on Flinders Island had its driest May on record and less than 25 mm fell through much of the East Coast and in the Derwent Valley, with only 9.6 mm recorded at Ouse. In the west totals reached 338 mm at Mount Read, but even this was below average.

The Midlands was one area that had near normal rainfall, after falls of around 10 mm on the 1st and 23rd. The far southeast around Bruny Island and the Tasman Peninsula were slightly wetter than usual with Premaydena (103 mm) having its wettest May since 1985.

Launceston's coldest May day on record

A cloudy day and cold airmass gave Launceston its coldest May day on record on the 12th, with a maximum of just 9.6 C (beating the previous record of 9.8 C set on 21 May 1982). This occurred during a period of cold weather from the 8th to the 14th when fronts brought showery conditions and mountain snow. Bicheno (12.1 C) and Strahan (9.2 C) had colder days than the whole of 2010, and Scottsdale (9.6 C) and Ross (7.6 C) had their coldest May day in over 15 years. Mount Wellington reached only -0.3 C on the 8th.

Days were warm between the 19th and 23rd (Bushy Park reached 22.8 C on the 22nd) but generally cool during the rest of the month. Average maximum temperatures were around half to one degree cooler than usual in most areas. Orford had its lowest May mean daily maximum temperature on record. Only a few sites in the Derwent Valley were warmer than usual.

Many cold and frosty nights

Cold and frosty nights were common during May, especially from the 5th to 15th and again from the 25th to 30th. The coldest temperatures were in the north, with Liawenee falling to -7.4 C on the 10th and -7.0 C on the 28th. Smithton recorded its coldest temperature since 1997 (-2.9 C on the 10th) and Devonport had its coldest May morning since 1994 (-0.5 C on the 28th).

Nights were warm on the 1st and from the 16th to 23rd, but it was still cooler than usual overall. Average minimum temperatures were one to two degrees below normal in the north and within half a degree of normal in the south. Eddystone Point (8.2 C) and Orford (4.4 C) had their lowest May mean daily minimum temperature in over 20 years.

Huge swells in the south and west

Following a cold outbreak on the 8th, several low pressure systems passed to the distant south of Tasmania generating huge southwest swells that affected the west and south coasts. The waverider near Strahan recorded a peak height of 12.7 metres early on the 14th, while swells at Cape Bruny reached 5 metres. A second peak occurred around midday on the 17th, with swells reaching 7 metres at Cape Bruny. Such large swells are rare in the southeast, but still well short of the extreme 10 metres reported at Cape Bruny in September 2010.

Hobart: little rain and some cold weather

Showers fell in Hobart on several days, but totals were small and for the whole month the city received only half its average May rainfall. This made it the first month this year with below average rainfall. The wettest day was 6.8 mm (to 9 am on the 24th), and the monthly total was 23.6 mm (the long-term average is about 46 mm).

There were several cold days: temperatures struggled to reach 13 C from the 8th to the 14th and peaked at just 10.4 C on the 24th in a cold southerly airsteam. In contrast, most days between the 16th and 23rd exceeded 18 C . Cold nights were also common, with the temperature falling below 4 C six times (this hasn't happened since 1969). Overall, both days (14.9 C) and nights (7.1 C) were slightly warmer than usual.

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Extremes in May 2011
Hottest day 22.8 C at Bushy Park (Bushy Park Estates) on the 22nd
Warmest days on average 15.8 C at Eddystone Point
Coolest days on average 5.0 C at Mount Read
Coldest day -0.3 C at Mount Wellington on the 8th
Coldest night -7.4 C at Liawenee on the 10th
Coolest nights on average -0.4 C at Liawenee
Warmest nights on average 10.6 C at Hogan Island
Warmest night 14.5 C at Burnie (Round Hill) on the 1st
14.5 C at Hogan Island on the 22nd
Warmest on average overall 12.7 C at Hogan Island
Coolest on average overall 2.7 C at Mount Wellington
Wettest overall 337.6 mm at Mount Read
Driest overall 9.6 mm at Ouse Fire Station
Wettest day 38.6 mm at Lake St Clair National Park on the 14th
Highest wind gust 128 km/h at Mount Wellington on the 15th

Maps

Observed Anomaly Decile 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



Highest total May rainfall for at least 20 years

Total rainfall
for May 2011 (mm)
Most recent May
at least this wet
Years since
wetter
Average for
May
Premaydena Hatchery 103.0 130.4 in 1985 25 65.6


Record lowest total May rainfall

Total rainfall
for May 2011 (mm)
Previous driest
for May
Years of
record
Average for
May
Memana (Babel Farm) 22.6 27.6 in 2005 49 77.8



Record lowest May daily maximum temperature

Lowest daily maximum
temperature
in May 2011 (C)
Previous coolest
for May
Years of
record
Average for
May
Launceston (Ti Tree Bend) 9.6 on the 12th 9.8 on the 21st in 1982 30 15.8



Record lowest May mean daily maximum temperature

Mean daily maximum
temperature
for May 2011 (C)
Previous coolest
for May
Years of
record
Average for
May
Orford (Aubin Court) 14.0 14.2 in 2001 42 15.7



Lowest May mean daily minimum temperature for at least 20 years

Mean daily minimum
temperature
for May 2011 (C)
Most recent May
at least this cool
Years since
cooler
Average for
May
Eddystone Point 8.2 7.2 in 1968 42 9.7
Orford (Aubin Court) 4.4 4.3 in 1979 32 6.2



Record lowest May mean temperature

Mean daily
temperature
for May 2011 (C)
Previous coolest
for May
Years of
record
Average for
May
Orford (Aubin Court) 9.2 9.6 in 2006 42 11.0





Summary statistics for May 2011
Maximum temperatures
for May
(C)
Minimum temperatures
for May
(C)
Rainfall
for May
(millimetres)
Mean for
May
2011
Diff
from
average
Highest for
May
2011
Mean for
May
2011
Diff
from
average
Lowest for
May
2011
Total for
May
2011
Average
for
May
Rank of
May
2011
Fraction of
May
average
Northern (district 91)
Bridport (Sea View Villas) 15.1 -0.8 18.8 17th 6.3 -1.6 1.2 14th 21.3 58.6 low 36%
Burnie (Round Hill) 15.4 +0.1 19.1 22nd 7.4 -1.0 3.0 14th 19.0 92.6 v low 21%
Cape Grim 13.7   17.4 22nd 9.5   5.5 10th 48.2
Cape Grim BAPS (Comparison) 14.0 -0.6 17.4 22nd 9.5 -0.7 6.1 14th 54.4 73.6 average 74%
Cressy Research Station 13.7 -1.2 18.7 22nd 1.7 -1.7 -5.3 28th 26.0 38.5 average 68%
Devonport Airport 14.6 -0.7 18.9 22nd 4.9 -1.9 -0.5 28th 29.8 72.7 low 41%
Launceston (Ti Tree Bend) 14.9 -0.9 19.2 22nd 3.1 -2.0 -2.0 28th 40.0 61.3 average 65%
Launceston Airport 13.7   19.5 22nd 2.5   -3.8 29th 32.6
Low Head 14.5 -0.9 18.0 22nd 7.7 -1.8 3.3 29th 53.8 54.6 average 99%
Luncheon Hill (Forestry) 12.1 -1.0 17.8 22nd 5.9 -1.1 1.2 9th 90.8 154.4 v low 59%
Marrawah 14.0 -0.7 17.8 22nd 8.5 -0.6 5.0 9th 71.4 102.5 low 70%
Scottsdale (West Minstone Road) 13.8 -1.1 17.6 22nd 4.2 -1.7 -0.3 14th 33.2 96.5 low 34%
Sheffield School Farm 13.0 -0.6 16.2 22nd 3.5 -2.0 -0.6 10th 41.0 79.2 low 52%
Smithton Aerodrome 14.4 -1.1 18.1 22nd 4.9 -1.3 -2.9 10th 33.6 78.3 low 43%
Wynyard Airport 15.0 -0.1 18.7 22nd 3.5 -1.8 -2.0 28th 25.2 96.8 v low 26%
East Coast (district 92)
Bicheno (Council Depot) 15.7 -0.9 19.8 21st 7.6 -0.9 2.5 12th 20.2 56.0 low 36%
Eddystone Point 15.8 0.0 18.8 20th 8.2 -1.5 3.1 14th 25.4 65.5 low 39%
Fingal (Legge Street) 13.9 -1.4 19.2 22nd 1.8 -1.1 -4.6 29th 20.8 50.0 low 42%
Friendly Beaches 15.2 -0.9 21.5 22nd 7.0 -1.3 1.6 29th 24.8 45.5 low 55%
Lake Leake (Elizabeth River) 10.3 -1.1 17.7 22nd 1.1 -1.0 -5.9 28th 41.2 72.7 average 57%
Maria Island (Point Lesueur) 13.9   18.2 22nd 8.9   5.1 14th 25.0
Orford (Aubin Court) 14.0 -1.7 19.5 22nd 4.4 -1.8 -0.5 31st 30.8 56.8 average 54%
Scamander 15.7 -0.9 20.9 22nd 6.4 -1.2 3.0 29th 18.3 50.8 low 36%
St Helens Aerodrome 15.2 -0.8 19.7 21st 5.9 -1.4 1.3 29th 20.4 34.4 low 56%
Swan Island 15.0   19.1 22nd 9.5   5.4 12th 24.8 43.8 average 57%
Swansea (Maria Street) 15.2   22.1 22nd 4.2   -2.1 28th 16.4
Midlands (district 93)
Ross (The Boulevards) 12.9 -1.5 18.5 22nd 2.0 -1.3 -6.2 28th 33.2 25.0 high 133%
Southeast (district 94)
Bull Bay (Lauriston) 14.2 -0.9 19.0 22nd 7.2 -0.9 3.9 10th 36.0 38.0 average 95%
Campania (Kincora) 14.8 -1.2 20.4 22nd 5.3 -0.4 0.1 28th 17.0 26.1 v low 65%
Cape Bruny (Cape Bruny) 13.6 -0.8 20.1 22nd 8.2 -0.5 4.4 14th 65.0 55.6 average 117%
Cape Bruny Lighthouse 13.3 -0.2 19.6 22nd 8.4 +0.1 4.7 15th 88.6 84.0 average 105%
Dover 14.1 -0.7 22.3 22nd 5.3 -0.5 0.4 10th 49.4 70.3 average 70%
Geeveston (Cemetery Road) 14.2 -0.4 21.7 22nd 4.9 +0.3 -0.8 10th 34.4 69.0 low 50%
Grove (Research Station) 14.1   21.6 22nd 3.8   -1.8 28th 34.8
Hobart (Ellerslie Road) 14.9 +0.5 22.0 22nd 7.1 +0.1 2.5 28th 23.6 46.2 low 51%
Hobart Airport 14.6 -0.6 21.0 22nd 6.8 +0.2 2.0 26th 25.4 34.2 average 74%
Maatsuyker Island Lighthouse 11.9 -0.9 19.4 22nd 8.4 0.0 4.3 14th 78.2 114.6 low 68%
Melton Mowbray (North Stockman) 13.1 -1.2 20.0 21st 3.9 -0.5 -3.1 10th 28.8 25.1 average 115%
Mount Wellington 5.3 -0.3 11.5 22nd 0.2 -0.4 -4.0 14th 35.2 61.1 low 58%
Tasman Island 12.2   17.8 20th 7.9   3.4 14th 62.8
Tunnack Fire Station 11.0 -1.5 15.9 22nd 2.8 -0.9 -4.0 28th 41.4 39.3 average 105%
Derwent Valley (district 95)
Bushy Park (Bushy Park Estates) 15.2 +0.9 22.8 22nd 3.0 -1.1 -2.1 9th 18.6 45.1 low 41%
Maydena Post Office 12.4 -0.7 21.2 22nd 4.5 +0.2 -1.5 9th 58.1 92.5 low 63%
Ouse Fire Station 15.0 +0.1 21.9 21st 3.0 -0.7 -3.8 31st 9.6 29.2 v low 33%
Tarraleah Village 10.5 -0.6 17.2 21st 3.0 +0.5 -2.5 9th 45.6 100.9 v low 45%
Central Plateau (district 96)
Butlers Gorge 9.7 -0.2 17.0 22nd 2.2 +0.5 -2.6 9th 97.0 158.2 low 61%
Lake St Clair National Park 9.1 -1.2 15.7 22nd 1.6 0.0 -4.9 10th 99.8 157.1 low 64%
Liawenee 8.7 -0.5 15.3 20th -0.4 -0.4 -7.4 10th 28.2 73.3 low 38%
West Coast (district 97)
Hartz Mountain (Keoghs Pimple) 7.3 -1.4 15.7 22nd 2.9 -0.6 -1.2 14th 62.6 68.5 average 91%
Mount Read 5.0 -1.5 11.4 22nd 1.1 -1.2 -2.4 14th 337.6 403.4 low 84%
Scotts Peak Dam 11.3 -0.3 20.5 22nd 5.5 -0.1 0.9 14th 160.4 160.1 average 100%
Strahan Aerodrome 13.4 -0.9 20.2 22nd 7.5 +0.2 0.8 9th 122.4 142.6 average 86%
Strathgordon Village 10.9 -0.6 19.8 22nd 5.4 +0.1 1.4 12th 187.2 239.9 average 78%
Warra 10.2   18.1 22nd 4.4   -1.0 10th 92.4
King Island (district 98)
King Island Airport 14.7 -0.9 19.2 21st 8.2 -1.1 3.8 28th 70.4 84.4 average 83%
Flinders Island (district 99)
Flinders Island Airport 15.4 -0.9 20.9 21st 8.1 -0.9 0.0 10th 21.2 78.5 v low 27%
Hogan Island 14.8   18.5 21st 10.6   6.9 11th 64.0
Antarctica and Macquarie Island (district 300)
Macquarie Island 5.9 0.0 7.9 21st 2.0 -0.5 -2.4 28th 100.4 83.0 high 121%


Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Tasmania 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 9 am on Wednesday 1 June 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 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.

Further information

Media
(03) 9669 4057
Enquiries