Monday, 1 August 2011 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

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

Extremes Maps Records Summaries Important notes the top

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.

---

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

Extremes Maps Records Summaries Important notes the top

---

Maps
	Observed	Anomaly	Decile rank
Total rainfall
Mean daily maximum temperatures
Mean daily minimum temperatures

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

Extremes Maps Records Summaries Important notes the top

---

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%

Extremes Maps Records Summaries Important notes the top

---

---