Friday, 1 August 2008 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in July 2008: cold and wet

Several low pressure systems passing close to Tasmania brought rain (and some snow) across the state at different times during July. It was cooler than usual for most of the month, with several bursts of cold winds and snow, however a lack of sustained westerly winds meant the West Coast had less than average rain.

An archive of previous monthly summaries for Tasmania is also available, as are summaries for other states and many other climate summaries and diagnostics.

Details

Low pressure systems bring rain: There was rain somewhere in the state on most days during July, in a marked change from the generally dry pattern seen in many recent months. Several low pressure systems that moved slowly past the ensured that there were some quite wet individual days, notably around the 1st, 18th and 21st. There were also several days with thunderstorms, some of which brought heavy rain or hail. Rainfall for the month as a whole displayed a complicated pattern, as individual weather events brought rain to some areas but not others. For much of the state, totals were close to average. However, it was above average along the western North West Coast, the northern East Coast and in parts of the Derwent Valley and southern Midlands. A lack of sustained westerly winds during the month meant it was drier than average on the West Coast and in the southwest; Maatsuyker Island had its driest July since 1932. It was also drier than average in some of the central north and the northeast of the state.

Long-term rain deficits continue: Most of Tasmania has been markedly drier than average for many months, with no sustained period of widespread rain since late 2005. Totals for 2008 so far are down on average in all but the northern East Coast (which had significant rain in February as well as July). For the 31 months between January 2006 to July 2008 almost all of the state has been the driest on record and much of the eastern half has received less than 70% of its normal rain. Rainfall deficits over the period exceed 500 mm in most parts of the state, and in some usually wet areas deficits exceed 1000 mm.

Cool days and snow: There were several bursts of cold weather through July, with five events that brought significant snow to the highlands: on the 2nd, 10th to 12th, 19th, 21st and 28th. The coldest of these was the 21st, where cold southerly winds from a low to the east of Tasmania kept the temperature below 10°C all day in most places and brought snow that settled below the 200 metre level in the south. Most days were cooler than average for July, with the main exceptions the 7th to 9th and the 14th. Averaged across the month, maximum temperatures were below average in almost all areas, typically by half to one degree. For many places it was the coldest June since 2004 or even 1995, and for Swansea it was the coldest since 1966.

Cold nights and frosts: Along with the cool days, there were many cold and frosty nights, especially the 4th to 6th, 19th to 27th, and the 29th to 31st. In most cases these occurred when a ridge of high pressure moved over the state in the wake of a cold front. On the morning of the 4th, Liawenee fell to −10.2°C, the coldest temperature recorded in Tasmania since May 2006 and the equal third coldest July temperature for the state. Liawenee also dropped below −9 °C on the 5th and 30th. Averaged across the month, minimum temperatures were below average across the state, typically by about half a degree near the north and east coasts but by one and half degrees in the southern inland. Hobart has not ha a lower July mean daily minimum temperature since 1982, Strathgordon equalled its record low mean daily minimum from 1971, and some other sites had their lowest for several decades.

Strong winds and high tides: Wind gusts over 100 km/h were reported from many places in the first few days of the month, and again around the 21st. High astronomical tides early in the month combined with low air pressure to cause inundation to some low-lying areas. Foggy mornings were also common in many areas, with the fog sometimes lingering well into the day.

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

Extremes

Hottest day
Highest temperature
17.7°C at Bicheno (Council Depot) on the 8th
Warmest days on average
Highest mean daily maximum temperature
13.6°C at Bicheno (Council Depot)
Coolest days on average
Lowest mean daily maximum temperature
1.9°C at Mount Wellington
Coldest day
Lowest daily maximum temperature
−2.6°C at Mount Wellington on the 21st
Coldest night
Lowest temperature
−10.2°C at Liawenee on the 4th
Coolest nights on average
Lowest mean daily minimum temperature
−2.6°C at Liawenee
Warmest nights on average
Highest mean daily minimum temperature
8.3°C at Hogan Island
Warmest night
Highest daily minimum temperature
11.6°C at Hogan Island on the 7th
Wettest overall
Highest total rainfall
270.8 mm at Cradle Valley (Waldheim)
The normally very wet Mt Read was not working this month
Driest overall
Lowest total rainfall
31.8 mm at Dodges Ferry
Wettest day
Highest daily rainfall
57.0 mm at Rosebery (Gepp Street) on the 11th
Highest wind gust
148 km/h at Maatsuyker Island Lighthouse on the 2nd

Records

Lowest total July rainfall for at least 20 years
Total rainfall
for July 2008 (mm)
Most recent lower
for July
Years since
lower
Normal for
July
Maatsuyker Island Lighthouse 61.2 51.0 in 1932 76 128.8



Lowest July mean daily maximum temperature for at least 20 years
Mean daily maximum
temperature
for July 2008 (°C)
Most recent lower
for July
Years since
lower
Normal for
July
Swansea Post Office 12.3 12.2 in 1966 42 13.3
Bushy Park (Bushy Park Estates) 10.5 10.4 in 1987 21 11.1



Record lowest July mean daily minimum temperature
Mean daily minimum
temperature
for July 2008 (°C)
Previous lowest
for July
Years of
record
Normal for
July
Strathgordon Village 1.9 = 1.9 in 1971 27 3.0


Lowest July mean daily minimum temperature for at least 20 years
Mean daily minimum
temperature
for July 2008 (°C)
Most recent lower
for July
Years since
lower
Normal for
July
Hobart (Ellerslie Road) 3.9 3.1 in 1982 26 4.5
Hobart Airport 3.2 2.5 in 1982 26 4.1
Grove (Comparison) 0.9 0.1 in 1982 23 2.0
Bushy Park (Bushy Park Estates) 0.1 −0.1 in 1987 21 1.5
Flinders Island Airport 4.5 3.5 in 1987 21 6.3


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 2008
Maximum temperatures
for July
(°C)
Minimum temperatures
for July
(°C)
Rainfall
for July
(millimetres)
Mean for
July
2008
Diff
from
normal
Highest for
July
2008
Mean for
July
2008
Diff
from
normal
Lowest for
July
2008
Total for
July
2008
Normal
for
July
Rank of
July
2008
Fraction of
July
normal
Northern (district 91)
Bridport     15.0 15th 5.2 −0.2 0.9 4th 77.2 73.6 average 105%
Burnie 12.7 0.0 14.9 7th 6.6 +0.7 2.2 4th 98.6 124.7 average 79%
Cape Grim BAPS 12.3 −0.2 14.4 6th 7.3 −0.9 3.3 29th 128.2 102.5 high 125%
Cressy Research Station 11.1 −0.9 15.7 8th 0.5 −1.2 −5.6 4th 57.6 60.7 average 95%
Devonport Airport 12.4 −0.3 15.0 16th 4.4 −0.2 0.6 23rd 76.4 96.6 average 79%
Launceston 12.4 −0.2 15.3 3rd 2.2 +0.1 −2.4 4th 54.0 75.8 low 71%
Launceston Airport 11.0   15.4 7th 1.5   −3.3 4th 42.8
Launceston Airport Comparison 10.6 −0.3 14.4 7th 1.7 −0.6 −3.3 4th
76.4

Low Head 12.2 −0.5 14.0 15th 6.3 −0.7 2.1 4th 83.6 69.5 high 120%
Luncheon Hill 10.1 −0.6 13.8 15th 4.3 −0.6 1.1 4th 171.4 182.5 average 94%
Marrawah 12.1 −0.2 14.5 14th 6.3 −0.4 2.5 28th 121.2 137.7 average 88%
Scottsdale 11.5 −0.5 14.8 7th 2.8 −0.9 −1.3 4th 69.0 118.9 low 58%
Sheffield School Farm 9.8 −1.1 12.6 14th 2.6 −0.8 −2.3 29th
112.6

Smithton Aerodrome 12.9 −0.2 15.0 31st 4.3 −0.3 −2.6 29th 132.2 114.4 average 116%
Wynyard Airport 12.5 −0.1 14.6 9th 3.2 −0.3 −2.4 4th 181.2 133.1 high 136%
East Coast (district 92)
Bicheno 13.6 −0.5 17.7 8th 5.6 −0.5 1.9 5th 70.8 53.2 average 133%
Eddystone Point 13.4 +0.3 16.2 8th 6.9 −0.1 2.5 22nd 100.2 77.1 high 130%
Fingal 11.3 −0.9 15.3 8th 0.3 −0.2 −5.5 4th 41.0 55.9 average 73%
Friendly Beaches 12.4 −1.4 16.5 7th 4.3 −1.5 −0.5 5th 74.4 48.5 average 153%
Lake Leake 7.7 −0.8 13.6 7th −0.9 −1.2 −7.6 4th 54.2 78.6 average 69%
Maria Island 11.9   16.5 7th 6.6   2.5 22nd 57.8
Orford 11.9 −1.2 16.2 7th 3.1 −0.4 −1.6 5th 43.2 58.7 average 74%
Scamander 13.2 −0.5 16.5 8th 4.4 −0.1 0.5 4th 75.5 56.6 high 133%
St Helens Aerodrome 12.8   16.0 8th 4.1   −0.3 4th 70.0
Swan Island 12.7   15.4 6th 7.6   4.7 23rd 95.2
Swansea Post Office 12.3 −1.0 15.6 9th 3.2 −0.4 −1.3 5th 52.8 48.0 average 110%
Midlands (district 93)
Ross 10.5 −0.8 15.7 8th 0.9 −0.5 −3.8 4th 47.2 40.9 high 115%
Southeast (district 94)
Bull Bay 11.3 −1.2 14.6 9th 4.5 −1.4 1.8 30th 59.0 55.2 average 107%
Campania 11.8   16.2 7th 2.4   −1.6 30th 53.6
Cape Bruny 11.3 −0.8 14.8 7th 5.5 −1.2 2.7 5th 67.4 72.5 average 93%
Cape Bruny Lighthouse 10.8 −0.4 14.3 7th 5.5 −0.6 3.0 5th 91.8 95.6 average 96%
Dover 11.4 −1.0 13.9 7th 1.7 −2.0 −2.1 25th 74.0 86.5 average 86%
Geeveston 11.2 −0.9 15.4 7th 0.6 −1.6 −3.9 5th 84.2 91.0 average 93%
Grove 11.1 −0.7 16.5 7th 0.9 −1.2 −3.9 5th 60.0 72.0 average 83%
Grove 11.2   16.7 7th 0.4   −4.5 4th 60.2
Hobart 11.7 0.0 15.8 7th 3.9 −0.7 0.3 30th 47.6 52.5 average 91%
Hobart Airport 11.9 −0.5 16.3 7th 3.2 −0.9 −0.3 25th 33.6 43.9 average 77%
Maatsuyker Island Lighthouse 11.2 +0.3 15.7 7th 6.7 +0.1 2.8 22nd 61.2 128.8 very low 48%
Melton Mowbray 9.9 −1.5 13.5 7th 0.7 −1.6 −4.0 30th 51.6 31.6 high 163%
Mount Wellington 1.9 −0.4 6.9 8th −2.2 −0.6 −5.8 22nd
76.2

Tasman Island 10.0   13.1 7th 6.0   1.1 22nd 71.0
Tunnack Fire Station 8.4 −1.2 12.8 8th 0.7 −1.2 −3.6 30th 53.2 46.0 high 116%
Derwent Valley (district 95)
Bushy Park 10.5 −0.6 14.9 8th 0.1 −1.4 −3.8 5th 48.0 49.5 average 97%
Maydena Post Office 9.4 −1.3 14.0 8th 0.9 −1.3 −2.4 5th 95.3 106.3 average 90%
Ouse Fire Station 10.1 −1.7 14.6 8th −0.2 −1.5 −5.1 5th 56.8 49.9 average 114%
Tarraleah Village     11.6 8th −0.1 −0.5 −3.9 5th 103.0 117.0 average 88%
Central Plateau (district 96)
Butlers Gorge 7.2 +0.3 11.8 8th −1.7 −1.3 −7.8 25th 151.8 175.5 average 86%
Lake St Clair National Park 6.5 −0.8 10.7 8th −1.5 −1.5 −6.0 26th 167.3 199.7 average 84%
Liawenee 4.6   8.5 14th −2.6   −10.2 4th 85.6
West Coast (district 97)
Hartz Mountain 5.5 −0.6 10.8 7th 0.6 −0.9 −2.8 22nd
89.3

Mount Read 3.0 −0.7 7.7 14th −0.7 −0.8 −3.9 22nd
341.5
Scotts Peak Dam 8.7   14.5 8th 1.6   −1.6 30th 172.4
Strahan Aerodrome 12.2 0.0 15.1 30th 3.9 −1.2 −0.8 28th 140.0 167.1 low 84%
Strathgordon Village 8.2 −0.8 12.1 7th 1.9 −1.1 −2.0 29th 209.1 268.2 average 78%
Warra 7.6   12.0 8th 1.3   −2.3 30th 154.0
King Island (district 98)
King Island Airport 13.3 +0.2 15.5 14th 6.3 −1.2 0.7 29th 109.6 112.0 average 98%
Flinders Island (district 99)
Flinders Island Airport 13.5 +0.2 17.2 14th 4.5 −1.8 −1.4 4th 79.2 84.7 average 94%
Hogan Island 12.8   15.3 6th 8.3   4.2 22nd 81.4
Antarctica and Macquarie Island (district 300)
Macquarie Island 5.0 +0.1 7.8 1st 2.0 +0.4 −3.2 4th 64.6 71.7 average 90%


Notes

This statement has been prepared based on information available at 9 am on Friday 1 August 2008. Extensive checks have been made on the data, but it is possible that results will change as new information becomes available.

Normals 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 ("normal") 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, normal in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of normal shows how much rain has fallen this time as a percentage of the long-term mean.

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