Monday, 3 August 2009 - Monthly Climate Summary for Tasmania - Product code IDCKGC27R0

Tasmania in July 2009: Consistent rain in the north, west and southeast

Rainfall for July was above average in western, northern and far southeastern Tasmania after cold fronts repeatedly brought moderate rainfalls to these areas and a particularly active front on the 11th and 12th delivered over 100 mm to some parts of the north. Totals were mostly near average for the remainder, but it was drier than usual in the central east and parts of the southern Midlands and Upper Derwent Valley. Minimum temperatures ranged from very cold to very warm but maximum temperatures were less variable.

An archive of previous monthly summaries for Tasmania is also available, as are summaries for other states and many other climate summaries and diagnostics. The next routine Climate Summaries for Tasmania, covering August and winter, are expected to be published on Tuesday 1 September 2009.

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Details

Fronts bring rain to the west, north and far southeast: Numerous fronts crossed the state during July repeatedly bringing moderate rainfall totals to the west, north and far southeast. The highest totals fell in northern areas on the 11th and 12th when a complex front crossed the state and an associated low passed near the west and south. Over 100 mm fell at several sites in the north in the 24 hours to 9 am on the 12th, and Mole Creek, Yolla, Barrington and Gowrie Park all had their wettest July day on record. This widespread heavy rain on already moist soils caused minor to moderate flooding of several rivers in the central north and northeast. The consistency of the rain in the west and north was also notable. At Strahan, for example, there were nine days when rainfall totals exceeded 15 mm; in a typical July this occurs only around three times. These two factors combined to give above average July rainfall to the west, north and far southeast, and some sites had their highest total July rainfall since 1975. Because the airflow was predominately westerly, it was drier than usual in the central east and parts of the southern Midlands and Upper Derwent Valley (this was in marked contrast to the wet June seen in the east). Elsewhere, rainfall was near normal.

Very warm and very cold nights: Very warm and very cold nights alternated during July, but over the whole month mean minima at most sites were near average or slightly warmer than normal. Hobart Airport did have its highest July mean minimum temperature since 1988, while Fingal and Orford were their warmest in July since 2001 and most other sites were their warmest for three or four years. On the 20th, many locations had their warmest July night in 10 or 15 years, including Devonport and Launceston which were their warmest since 1994. The 1st, 12th and 29th and 30th were also much warmer than usual. In contrast, some sites had their coldest July night in 10 or 15 years on the 24th. One such site was Friendly Beaches, which fell to −0.9°C and hasn't recorded a July temperature this cold since it opened in 1997. Other very cold nights were the 7th to the 10th, 17th and 18th. Liawenee fell below −7°C four times; something that would usually be expected only twice in July.

Mostly near average days: Daytime temperatures in July were not as extreme as overnight temperatures and on most days maxima were not too far from average. The coldest days were around the 6th and 16th as a southerly airstream suppressed temperatures, but most sites still managed to reach at least nine or ten degrees. It was also very cold in the Derwent Valley on the 8th and 10th when fog that formed overnight failed to clear during the day. Bushy Park only managed to reach 2.7°C on the 8th. The 20th and 21st were much warmer, and most maxima reached the mid to high teens on these days. On the 20th Friendly Beaches had the warmest temperature for the month (19.7°C), and Bicheno (18.6°C) had its warmest July day since 1994. Mean maxima across the state were mostly within half a degree of normal, generally cooler than normal except for parts of the north and east. Many sites in the north and east had their warmest July for three or four years. 

Further information

Ian Barnes-Keoghan
Meteorologist
Tasmania and Antarctica Climate Services Centre
Bureau of Meteorology
Phone (03) 6221 2043
Email climate.tas@bom.gov.au

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Extremes

Hottest day Highest temperature	19.7°C at Friendly Beaches on the 20th
Warmest days on average Highest mean daily maximum temperature	14.4°C at Bicheno (Council Depot)
Coolest days on average Lowest mean daily maximum temperature	2.1°C at Mount Wellington
Coldest day Lowest daily maximum temperature	−2.3°C at Mount Wellington on the 6th
Coldest night Lowest temperature	−8.6°C at Liawenee on the 17th
Coolest nights on average Lowest mean daily minimum temperature	−1.8°C at Mount Wellington
Warmest nights on average Highest mean daily minimum temperature	9.1°C at Hogan Island
Warmest night Highest daily minimum temperature	12.8°C at Low Head on the 20th
Wettest overall Highest total rainfall	585.8 mm at Mount Read
Driest overall Lowest total rainfall	14.8 mm at Friendly Beaches
Wettest day Highest daily rainfall	123.6 mm at Mole Creek on the 12th
Highest wind gust	137 km/h at Maatsuyker Island Lighthouse and Scotts Peak Dam on the 20th

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Records

Record highest July daily rainfall
	Highest daily rainfall in July 2009 (mm)		Previous highest for July		Years of record
Yolla (Sea View)	119.4	on the 12th	97.3	on the 5th in 1963	103
Mole Creek	123.6	on the 12th	79.5	on the 15th in 1951	93
Barrington Post Office	99.0	on the 12th	75.8	on the 21st in 2000	43
Gowrie Park	84.0	on the 12th	61.0	on the 21st in 2000	34

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Highest total July rainfall for at least 20 years
	Total rainfall for July 2009 (mm)	Most recent higher for July		Years since higher	Average for July
Savage River Mine	348.0	376.4	in 1972	36	236.5
King Island Airport	166.8	214.8	in 1975	34	113.9
Marrawah	230.4	242.4	in 1975	34	140.0
Yolla (Sea View)	275.4	382.4	in 1975	34	192.8
Mole Creek	241.4	330.6	in 1975	33	148.1
Naracoopa	197.8	218.8	in 1975	33	127.1
Yambacoona	162.2	233.2	in 1975	30	115.7

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Highest July mean daily minimum temperature for at least 20 years
	Mean daily minimum temperature for July 2009 (°C)	Most recent higher for July		Years since higher	Average for July
Hobart Airport	5.2	5.3	in 1988	21	4.1

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Summaries

In this table, key sites have been highlighted to make them easier to find. This table is very wide and may not fit if printed.

Summary statistics for July 2009
	Maximum temperatures for July (°C)				Minimum temperatures for July (°C)				Rainfall for July (millimetres)
	Mean for July 2009	Diff from average	Highest for July 2009		Mean for July 2009	Diff from average	Lowest for July 2009		Total for July 2009	Average for July	Rank of July 2009	Fraction of July average
Northern (district 91)
Bridport	13.2	0.0	15.5	20th	5.4	−0.1	1.2	7th	112.6	76.8	very high	147%
Burnie	13.1	+0.4	14.6	19th	6.4	+0.5	2.0	7th	115.2	124.6	average	92%
Cape Grim BAPS	12.6	+0.1	14.5	19th	8.2	0.0	3.4	7th	150.2	103.3	very high	145%
Cressy Research Station	11.6	−0.2	15.3	30th	1.2	−0.3	−4.6	17th	73.6	61.9	average	119%
Devonport Airport	13.0	+0.3	15.6	4th	5.1	+0.5	−0.5	7th	82.2	96.5	average	85%
Launceston	13.0	+0.4	15.1	29th	2.6	+0.4	−2.3	17th	92.2	76.6	high	120%
Launceston Airport	11.8		14.6	30th	2.2		−3.5	17th	78.8
Low Head	12.9	+0.2	14.6	20th	7.2	+0.3	1.2	7th	82.0	70.9	average	116%
Luncheon Hill	10.2	−0.4	13.1	9th	4.9	0.0	1.1	7th	253.6	187.9	high	135%
Marrawah	12.3	+0.1	15.0	19th	7.0	+0.4	2.0	7th	230.4	140.0	very high	165%
Scottsdale	11.8	−0.1	14.3	20th	3.8	+0.1	−0.8	31st	141.2	119.5	average	118%
Sheffield School Farm	10.9	+0.1	14.1	19th	3.0	−0.3	−2.5	17th	210.4	121.5	very high	173%
Smithton Aerodrome	12.8	−0.3	15.8	19th	4.6	0.0	−2.4	7th	129.0	115.6	average	112%
Wynyard Airport	13.0	+0.4	15.3	19th	3.3	−0.1	−2.4	7th	136.6	132.9	average	103%
East Coast (district 92)
Bicheno	14.4	+0.4	18.6	20th	6.1	0.0	1.2	24th	30.0	52.9	low	57%
Eddystone Point	13.7	+0.7	16.1	10th	7.1	+0.1	2.7	7th	75.8	76.5	average	99%
Fingal	12.3	+0.2	16.2	30th	1.5	+1.0	−4.2	24th	29.8	55.7	low	54%
Friendly Beaches	13.6	−0.1	19.7	20th	5.6	−0.1	−0.9	24th	14.8	45.7	low	32%
Lake Leake	8.3	−0.1	12.2	20th	0.5	+0.3	−5.7	24th	69.2	78.1	average	89%
Maria Island	12.4		16.2	30th	7.4		4.3	24th	47.4
Orford	12.7	−0.3	16.8	20th	4.3	+0.8	−1.0	8th	51.2	58.6	average	87%
Scamander	14.1	+0.3	17.5	30th	4.8	+0.3	0.5	18th	38.6	55.7	average	69%
St Helens Aerodrome	13.4		16.2	20th	4.8		−0.4	18th	64.8
Swan Island	13.3		15.5	10th	8.4		4.1	7th	70.8
Swansea Post Office	13.6	+0.3	17.9	20th	3.9	+0.3	−1.8	24th	20.6	47.8	low	43%
Midlands (district 93)
Ross	11.3	+0.1	14.7	30th	2.0	+0.5	−3.8	24th	44.6	41.1	average	109%
Southeast (district 94)
Campania	12.7		17.4	20th	3.8		−0.9	8th	29.2	36.1	average	81%
Cape Bruny	11.6	−0.4	15.8	20th	6.5	−0.2	2.6	8th	103.8	74.9	high	139%
Cape Bruny Lighthouse	11.3	+0.1	15.5	20th	6.4	+0.3	3.0	8th	139.4	95.7	high	146%
Dover	11.8	−0.5	15.4	30th	3.7	+0.1	−1.9	8th	85.6	85.9	average	100%
Geeveston	11.8	−0.2	15.3	19th	2.6	+0.4	−2.6	18th	93.8	91.0	average	103%
Grove	12.0		16.1	20th	2.3		−3.5	18th	66.4
Hobart	12.5	+0.8	17.2	20th	5.3	+0.8	0.5	8th	39.0	52.4	average	74%
Hobart Airport	12.4	0.0	17.2	20th	5.2	+1.2	1.3	8th	43.2	43.9	average	98%
Maatsuyker Island Lighthouse	10.8	−0.2	14.3	12th	7.0	+0.4	4.7	7th	188.2	129.3	high	146%
Melton Mowbray	10.9	−0.4	15.7	20th	2.7	+0.6	−3.3	8th	24.0	31.0	average	77%
Mount Wellington	2.1	−0.2	6.6	8th	−1.8	−0.1	−5.4	24th	81.6	73.8	average	111%
Tasman Island	10.7		16.0	20th	6.4		3.5	7th	87.2
Tunnack Fire Station	9.0	−0.5	12.9	19th	1.8	0.0	−3.3	24th	34.2	45.1	low	76%
Derwent Valley (district 95)
Bushy Park	11.6	+0.5	16.3	20th	1.3	−0.2	−3.8	24th	39.6	49.4	average	80%
Maydena Post Office	9.9	−0.8	14.9	20th	2.6	+0.4	−1.3	9th	123.9	107.6	average	115%
Ouse Fire Station	11.4	−0.3	15.4	20th	1.3	+0.2	−4.6	17th	31.2	48.4	low	64%
Tarraleah Village	8.1	−0.2	11.0	19th	1.2	+0.9	−3.0	17th	108.0	116.9	average	92%
Central Plateau (district 96)
Butlers Gorge	7.5	+0.6	10.1	19th	0.6	+1.1	−6.6	8th	192.2	175.8	average	109%
Lake St Clair National Park	6.9	−0.4	9.5	20th	0.1	+0.2	−5.5	8th	272.7	203.3	high	134%
Liawenee	5.3		9.1	30th	−1.5		−8.6	17th	170.0
West Coast (district 97)
Hartz Mountain	5.1	−1.0	8.6	8th	1.1	−0.3	−1.0	17th	127.6	96.0	very high	133%
Mount Read	3.3	−0.3	5.7	15th	−0.2	−0.2	−3.1	7th	585.8	394.7	high	148%
Scotts Peak Dam	8.5		12.2	14th	3.3		−0.9	10th	296.2	192.5	very high	154%
Strahan Aerodrome	12.1	−0.1	14.8	10th	5.4	+0.4	−1.6	16th	309.8	162.9	very high	190%
Strathgordon Village	9.0	+0.1	12.2	20th	3.5	+0.6	−1.2	8th	378.5	271.0	high	140%
Warra	8.1		11.5	19th	2.7		−2.7	8th
King Island (district 98)
King Island Airport	13.4	+0.2	15.9	19th	7.7	+0.3	2.1	17th	166.8	113.9	very high	146%
Flinders Island (district 99)
Flinders Island Airport	13.8	+0.6	18.2	21st	7.4	+1.1	−1.4	7th	58.0	84.4	low	69%
Hogan Island	12.9		17.6	21st	9.1		6.8	2nd	125.0
Antarctica and Macquarie Island (district 300)
Macquarie Island	4.2	−0.7	6.7	1st	1.0	−0.6	−6.0	18th	58.6	71.5	average	82%

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Notes

Further information

Ian Barnes-Keoghan
Meteorologist
Tasmania and Antarctica Climate Services Centre
Bureau of Meteorology
Phone (03) 6221 2043
Email climate.tas@bom.gov.au

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