Tasmania in July 2011: Cool, strong winds, huge waves, snow

There was some mild weather at the end of the month, but most of July was cool. The 9th and 10th saw two vigorous cold fronts deliver snow down to 150 m, as well as record waves and damaging winds. It was drier than average in the east and the far northwest.

  • Record cold night at Liawenee with -11.2 °C on the 23rd
  • Record warm July nights at some spots on the 29th
  • Record 18.68 m wave recorded at Cape Sorell
  • Marked rainfall contrast across Hobart

Wild winds, waves and snow

The most notable event of the month was on the 9th and 10th when two strong cold fronts crossed the state, with the vigorous westerly flow producing damaging winds about the southeast on the 9th, and right across Tasmania on the 10th. Trees were reported down on the 9th, with power outages affecting several thousands of premises due to damaged power lines. The highest wind gust of 178 km/h was recorded at Mount Wellington on the 10th, with Maatsuyker Island reporting 176 km/h.

Wave and swell heights were also significant with this event. On the 9th damaging surf demolished several jetties on the Tasman Peninsula, with flooding and coastal erosion about the southeast of the state including Lauderdale and Port Arthur. The waverider buoy off Cape Sorell recorded very large waves, reaching its highest ever maximum wave height of 18.68 metres on the morning of the 11th, which exceeds the 18.4 m reported in September 2010 and approaches the record wave of 19.8 metres measured by a similar buoy operated by CSIRO in July 1985. Cape Bruny and Maatsuyker Island reported swells up to 11 metres.  

Snow falls were down to 150 m in the south on the 10th and 11th in the cold airstream following the fronts, with several road closures as a result. Minor flooding of the Huon River was also reported.

Little rainfall for the east and far northwest

July was a drier month than June overall, especially across eastern parts of the state and in the far northwest corner. Launceston only received half of its monthly average with 38 mm, after having received close to double the monthly average in June. This is Launceston’s driest July in 10 years (37 mm was recorded in July 2001). Several other sites across the north and east received less than half their monthly average. The driest site was Maria Island (Point Lesueur) with 13.4 mm for the month.

The Derwent Valley, Central Plateau and parts of the southeast did receive above average rainfall, with rainfall totals ranging from 70 mm up to 300 mm. Most of this fell between the 3rd and the 15th, when showers and rain were common about the west and south of the state.

The passage of a low pressure system over Bass Strait delivered more rain to the north west of the state on the 18th with Yolla recording 31 mm. On the 21st, a high pressure system to the south of Tasmania directed a moist easterly flow across the state, with Mount Victoria receiving 25 mm.

Many cool days, but a warm finish

Most July days were noticeably cooler than usual, but the last four days of the month were quite mild. Until that warm spell, several locations were on track to record their coldest July for several years. The coldest days were the 5th, 10th and 13th in the very cold southwesterly flow following the passage of cold fronts. Maximum temperatures were up to 4 to 6 °C below average, with Mount Wellington recording the 3 coldest days of the month on these days, the lowest being a maximum of only -2.9 °C on the 10th.

The end of the month saw the mildest days as northerly winds pushed temperatures into the high teens in several locations. Swansea reached 18.7 °C on the 29th, and Scamander was not far behind with 18.6 °C on the 30th and 31st. There was also some mild weather at the start of the month and around the 18th.

Record cold July night and record warm July nights

Liawenee recorded the coldest night, with -11.2 °C on the 23rd. This is the coldest temperature ever recorded at Liawenee, and the second-coldest July temperature recorded in Tasmania (the lowest recorded July temperature is -12.5 °C at Butlers Gorge on 1 July 1983, one day after recording the state’s lowest-ever temperature of -13.0 °C on 30 June 1983).

The coldest nights for most sites were from the 14th to the 16th as a ridge of high pressure moved in over Tasmania, and from the 23rd to the 27th.

At the other extreme, the warmest nights were at the start of the month and at the end of the month in warm northerly airstreams. The morning of the 29th was particularly warm, with Bushy Park, Butlers Gorge, Tarraleah and Strahan all recording their warmest July night on record.

Overall, monthly minimum temperatures were within a degree of average, though tending on the warm side in the north and on the cool side in the south.

Hobart:  almost the coldest July in 16 years, thwarted by a warm finish

The first four weeks of July had Hobart on track to experience its coldest July since 1995. This came to an end with a mild final 4 days of the month, reaching a balmy 17.7 °C on the 29th. This pushed the overall mean maximum temperature up to 12.0 °C, which is just warmer than average. Nights were warm at the end of the month too, with the minimum dropping to only 11.0 °C on the morning of the 29th. The overall mean minimum temperature was 4.2 °C, which is just below average.

There was a notable contrast in rainfall across the Hobart area in July, with the western shore receiving much more rain than the eastern shore.  The gauge at Battery Point received close to its monthly average with 50 mm recorded over 17 days, whereas Hobart Airport received only 20 mm, which is less than half its monthly average. Similar contrasts were seen elsewhere across the Hobart area including 83 mm recorded at Kingston and 60 mm at Taroona compared to 27 mm at Rokeby and Bellerive.

The bulk of the month’s rainfall fell between the 9th and the 11th (30.4 mm over these 3 days) associated with the passage of two vigorous cold fronts, which also delivered snow down to 150 m in the Hobart area, closing some roads.

Further information

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Extremes in July 2011
Hottest day 18.7 °C at Swansea (Maria Street) on the 29th
Warmest days on average 13.7 °C at Bicheno (Council Depot) and Scamander
Coolest days on average 2.1 °C at Mount Wellington
Coldest day -2.9 °C at Mount Wellington on the 10th
Coldest night -11.2 °C at Liawenee on the 23rd
Coolest nights on average -2.4 °C at Liawenee
Warmest nights on average 8.6 °C at Hogan Island
Warmest night 12.2 °C at Cape Sorell on the 2nd
Warmest on average overall 10.6 °C at Hogan Island
Coolest on average overall -0.1 °C at Mount Wellington
Wettest overall 366.3 mm at Strathgordon Village
Driest overall 13.4 mm at Maria Island (Point Lesueur)
Wettest day 58.4 mm at Lake St Clair National Park on the 10th
Highest wind gust 178 km/h at Mount Wellington on the 10th

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 July rainfall for at least 20 years

Total rainfall
for July 2011 (mm)
Most recent July
at least this wet
Years since
wetter
Average for
July
Lake St Clair National Park 321.8 362.4 in 1990 21 205.3
Geeveston (Cemetery Road) 156.0 186.0 in 1990 20 91.7



Lowest total July rainfall for at least 20 years

Total rainfall
for July 2011 (mm)
Most recent July
at least this dry
Years since
drier
Average for
July
Lilydale Post Office 42.2 30.2 in 1971 39 123.8



Record lowest July daily maximum temperature

Lowest daily maximum
temperature
in July 2011 (°C)
Previous coolest
for July
Years of
record
Average for
July
Lake Leake (Elizabeth River) 2.9 on the 5th = 2.9 on the 9th in 1997 22 8.5



Record highest July daily minimum temperature

Highest daily minimum
temperature
in July 2011 (°C)
Previous warmest
for July
Years of
record
Average for
July
Bushy Park (Bushy Park Estates) 10.6 on the 29th 10.5 on the 3rd in 1985 49 1.4
Butlers Gorge 7.7 on the 29th 7.5 on the 17th in 1979 37 -0.4
Tarraleah Village 7.9 on the 29th 7.5 on the 3rd in 1985 29 0.4
Strahan Aerodrome 11.6 on the 29th 11.5 on the 19th in 2002 20 5.0



Summary statistics for July 2011

Maximum temperatures
for July
(°C)
Minimum temperatures
for July
(°C)
Rainfall
for July
(millimetres)
Mean for
July
2011
Diff
from
average
Highest for
July
2011
Mean for
July
2011
Diff
from
average
Lowest for
July
2011
Total for
July
2011
Average
for
July
Rank of
July
2011
Fraction of
July
average
Northern (district 91)
Bridport (Sea View Villas) 12.9 -0.4 16.7 18th 3.8 -1.6 0.0 7th 25.8 73.6 v low 35%
Burnie (Round Hill) 12.7 0.0 17.3 18th 7.1 +1.2 3.1 27th 103.7 123.6 average 84%
Cape Grim 11.9   14.4 1st 7.6   4.2 20th 80.4


Cape Grim BAPS (Comparison) 11.9 -0.6 14.7 29th 7.6 -0.6 3.6 21st 67.4 100.8 low 67%
Cressy Research Station 11.5 -0.4 16.4 29th 2.2 +0.8 -4.3 15th 31.8 58.5 low 54%
Devonport Airport 12.2 -0.5 15.5 18th 4.7 +0.1 -1.7 27th 60.2 95.4 low 63%
Launceston (Ti Tree Bend) 12.7 +0.1 16.9 29th 2.7 +0.5 -2.6 15th 38.4 75.6 v low 51%
Launceston Airport 11.5   16.7 29th 1.8   -3.7 16th 42.0


Low Head 12.1 -0.6 14.2 29th 6.6 -0.3 1.0 27th 22.6 68.7 v low 33%
Luncheon Hill (Forestry) 10.0 -0.7 14.4 29th 4.4 -0.6 0.5 21st 187.8 185.3 average 101%
Marrawah 12.0 -0.3 15.0 29th 6.8 +0.1 2.5 20th 88.6 138.2 low 64%
Scottsdale (West Minstone Road) 11.6 -0.4 15.4 18th 3.6 -0.1 -2.1 14th 50.8 117.5 low 43%
Sheffield School Farm 10.3 -0.5 14.5 29th 3.2 -0.1 -1.2 23rd 96.6 118.1 average 82%
Smithton Aerodrome 12.5 -0.6 16.1 31st 5.3 +0.8 -2.3 20th 84.6 110.5 average 77%
Wynyard Airport 12.4 -0.2 16.3 19th 4.1 +0.7 -2.5 14th 122.2 131.3 average 85%
East Coast (district 92)
Bicheno (Council Depot) 13.7 -0.4 16.7 31st 6.0 -0.1 0.7 6th 36.0 52.6 average 68%
Eddystone Point 13.3 +0.2 16.2 2nd 6.9 -0.2 1.2 14th 25.8 75.7 v low 34%
Fingal (Legge Street) 11.8 -0.4 16.8 29th 0.8 +0.3 -5.4 27th 36.0 55.5 average 65%
Friendly Beaches 13.0 -0.7 17.1 29th 5.0 -0.6 -0.6 16th 34.0 44.0 average 77%
Lake Leake (Elizabeth River) 7.7 -0.8 11.9 29th -0.1 -0.3 -6.3 16th 49.6 77.4 low 64%
Maria Island (Point Lesueur) 11.8   15.7 29th 6.8   3.5 11th 13.4


Orford (Aubin Court) 12.1 -1.0 17.0 29th 3.2 -0.3 -2.8 16th 14.7 57.1 v low 26%
Scamander 13.7 -0.1 18.6 31st 4.8 +0.3 -1.2 6th 21.7 55.0 low 39%
St Helens Aerodrome 13.0 -0.5 16.6 30th 4.1 -0.7 -0.1 15th 26.0 48.8 low 53%
Swan Island 12.7   15.9 2nd 8.2   4.0 15th 20.8 59.6 v low 35%
Swansea (Maria Street) 12.9   18.7 29th 2.9   -2.8 27th 16.6


Midlands (district 93)
Ross (The Boulevards) 10.8 -0.4 14.3 18th 1.1 -0.3 -6.5 27th 24.0 39.1 low 61%
Southeast (district 94)
Bull Bay (Lauriston) 11.5 -1.0 16.9 31st 4.9 -0.9 1.5 25th 49.3 53.7 average 92%
Campania (Kincora) 12.3 -0.8 18.2 28th 3.0 -0.2 -2.2 25th 37.6 33.7 average 112%
Cape Bruny (Cape Bruny) 11.3 -0.8 16.7 29th 5.6 -1.0 2.2 23rd 105.2 74.3 high 142%
Dover 11.8 -0.5 18.0 29th 3.0 -0.6 -1.8 25th 101.4 85.4 average 119%
Geeveston (Cemetery Road) 11.3 -0.8 17.1 29th 2.1 -0.1 -2.9 24th 156.0 91.7 v high 170%
Grove (Research Station) 11.3   17.5 29th 1.4   -4.7 27th 85.2


Hobart (Ellerslie Road) 12.0 +0.3 17.7 29th 4.5 -0.1 0.6 25th 50.2 52.0 average 97%
Hobart Airport 12.3 -0.1 17.8 28th 4.1 0.0 -1.1 15th 20.0 42.8 low 47%
Maatsuyker Island Lighthouse 10.7 -0.3 16.0 1st 6.8 +0.2 1.3 11th 78.6 128.5 low 61%
Melton Mowbray (North Stockman) 10.3 -1.1 16.2 28th 0.9 -1.1 -5.1 24th 45.4 30.4 high 149%
Mount Wellington 2.1 -0.2 8.4 29th -2.1 -0.5 -6.0 7th



Tasman Island 10.1   15.5 1st 5.7   1.4 7th 90.4 72.9 high 124%
Tunnack Fire Station 8.6 -0.9 14.9 29th 0.9 -0.8 -5.6 24th 43.8 45.0 average 97%
Derwent Valley (district 95)
Bushy Park (Bushy Park Estates) 10.8 -0.3 18.0 28th 1.0 -0.4 -4.9 25th 86.8 49.4 v high 176%
Maydena Post Office 9.6 -1.1 16.1 30th 1.2 -1.0 -3.5 24th 198.9 109.1 v high 182%
Ouse Fire Station 10.4 -1.3 18.4 29th 0.6 -0.4 -5.0 23rd 75.6 47.6 high 159%
Tarraleah Village 7.2 -1.1 13.1 31st     -6.0 23rd 151.8 116.5 high 130%
Central Plateau (district 96)
Butlers Gorge 6.9 -0.1 12.3 29th -0.6 -0.2 -6.3 16th 255.4 175.6 high 145%
Lake St Clair National Park 6.2 -1.1 11.6 29th -0.8 -0.7 -5.9 23rd 321.8 205.3 v high 157%
Liawenee 5.1 -0.5 11.5 29th -2.4 -0.8 -11.2 23rd



West Coast (district 97)
Cape Sorell 12.0 +0.3 15.3 1st 7.2 +0.1 2.8 24th 114.6 155.7 low 74%
Hartz Mountain (Keoghs Pimple) 5.6 -0.4 12.6 1st 0.8 -0.6 -3.2 7th



Mount Read 2.8 -0.9 7.3 1st -0.8 -0.9 -3.7 6th



Scotts Peak Dam 8.7 -0.6 13.3 1st 2.2 -1.0 -2.3 24th



Strahan Aerodrome 11.7 -0.5 16.6 1st 5.0 0.0 -2.1 24th 177.4 171.0 average 104%
Strathgordon Village 8.2 -0.8 14.1 29th 2.2 -0.8 -1.8 24th 366.3 271.6 high 135%
Warra 8.5   13.8 29th     -3.0 23rd



King Island (district 98)
King Island Airport 12.9 -0.3 15.6 31st 8.1 +0.6 4.4 23rd 69.2 112.6 low 61%
Flinders Island (district 99)
Flinders Island Airport 13.2 -0.1 17.3 30th 6.6 +0.3 -1.5 15th 34.0 83.4 v low 41%
Hogan Island 12.5   16.1 30th 8.6   5.7 6th 111.4


Antarctica and Macquarie Island (district 300)
Macquarie Island 3.7 -1.2 7.2 2nd -0.2 -1.8 -6.5 24th 65.2 71.5 average 91%

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 10 am on Monday 1 August 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