Wednesday, 4 January 2006

Annual Climate Summary – Tasmania

From dry to wet, and warm with it

Variability is one of the main features of Tasmania's weather. Marked changes can occur in just a few hours, or just a few kilometres. Looking across a whole year, it is possible to see a wide range of weather, and examining just the averages often obscures the more extreme events. This is a short summary of the main features of Tasmania's weather during 2005.

A dry first half: The first five or six months of 2005 saw less rain than normal, especially in the north of Tasmania which missed out on some very heavy falls in February. Launceston was one site that had itsdriest January-to-June on record.

A wet second half: The last week of July was wet in the north, the start of many months of wet weather. There were many very wet days over the next five months, and northern rivers flooded several times. Launceston (among others) had its wettest July-to-December on record.

Warm nights: Average minimum (overnight) temperatures were above normal across Tasmania, typically by around half a degree. Averaged across the whole state, this is the 4th-warmest for minimum temperatures, as the Annual Australian Climate Summary shows. It was also enough to give record highest mean minimum temperatures to a few sites.

Warm days: Average maximum (daytime) temperatures were also above normal, although not by as much as the minima. Differences from normal were greatest in the southeast, where a few sites had record highest mean maximum temperatures.

Snow to sea level: There were a number of major weather events during the year, including a cold outbreak that brought snow to sea level in the southeast on the 10th and 11th of August, along with some record cold days.

Weather extremes during 2005

Highest temperature
Hottest day
36.8 °C Bushy Park on 26th Jan
Highest mean daily maximum temperature
Warmest days on average
18.8 °C Campania
Lowest mean daily maximum temperature
Coolest days on average
8.7 °C Mount Read
Lowest daily maximum temperature
Coldest day
-5.0 °C Mount Wellington on 11th Aug
Lowest temperature
Coldest night
-8.0 °C Liawenee on 26th Jun
Lowest mean daily minimum temperature
Coldest nights on average
1.9 °C Liawenee
Highest mean daily minimum temperature
Mildest nights on average
11.7 °C Swan Island
Highest daily minimum
Warmest night
20.4 °C Flinders Island Airport on 3rd Nov
Highest total rainfall
Wettest overall
4031 mm Mount Read
Lowest total rainfall
Driest overall
459 mm Hamilton (Clyde River)
Highest daily rainfall
Wettest day
250.8 mm Breona (Lower Haulage Road) on 31st Aug
Hottest day: 36.8 °C at Bushy Park on 26 January

The last week of January 2005 was warm and unsettled, with several outbreaks of thunderstorms.  The 25th and 26th were especially warm in the southeast, with many sites reaching into the 30s. The warmest was at Bushy Park in the Derwent Valley, where it reach 36.8 °C on Australia Day,Tasmania's highest temperature for 2005 (but well short of the record 40.8 °C recorded in Hobart in 1976).

Coldest night, coldest nights on average: Liawenee

Liawenee on the Central Plateau often has the coldest nights in Tasmania during winter, because it is away from the sea and high up. Liawenee's average minimum (overnight) temperature for 2005 was 1.9 °C, the lowest for anywhere in Tasmania. There were several cold nights as a high passed over Tasmania near the end of June, and on the morning of 26 June the temperature at Liawenee dropped to –8.0 °C, the lowest temperature recorded during 2005.

Warmest days on average: 18.8 °C at Campania

An Automatic Weather Station (or AWS) was installed at Campania (north of Richmond) in 2001. It is proving to be one of the warmer places in the state, often registering the highest temperature on warm to hot days. In 2005, its average daily maximum was 18.8 °C, the warmest in the state but just 0.1 degrees warmer than Swansea.

Coldest day: -5.0 °C on Mount Wellington on 11 August

A cold outbreak brought snow to sea level on the 10th and 11th of August. It was the biggest snow event in the south of the state since 1986, closing the the Southern Outlet into Hobart (among other roads) for several hours on the morning of the 11th. Several sites had their lowest-ever August maximum temperature.The temperature did not rise above -5.0 °C on Mount Wellington on the 11th, the lowest maximum temperature ever recorded in Tasmania in any month.

Coldest days on average: 8.7 °C on Mount Read

The automatic weather station on Mount Read in the West Coast Range south of Rosebery is 1119 metres above sea level, lower than that on Mount Wellington (1261 metres). But Mount Read experienced fewer warm temperatures (Mount Wellington's highest for 2005 was 27.8 °C, whilst Mount Read's was only 23.9 °C), so had cooler days on average.

Warmest nights on average: 11.7 °C at Swan Island

Warmer than normal nights were quite common during 2005, with a few sites reaching their record highest mean daily minimum temperature for a year, and many records set in individual months. Proximity to the relatively warm waters of the Tasman Sea ensures the northeast coast has the mildest nights on average in Tasmania. The average minimum (that is, overnight) temperature for the year at Swan Island (off the northeast tip) was 11.7 °C. Very cold nights are rare there, although it did drop to 2.6 °C on 12 August (a morning when many other parts of the State recorded sub-zero temperatures).

Mildest night: 20.4 °C at Flinders Island Airport on 2/3 November

The temperature at Flinders Island Airport did not drop below 20.4 °C on 3 November. This was one of several sites to have their highest November minimum temperature on that day, but the Flinders Island value is the highest November minimum temperature for Tasmania.

Wettest day: 250.8 mm at Breona  to 9 am on 31 August

Very heavy rain fell in the north late in August, especially in the early morning of the 31st. Breona (on the north of Great Lake) received 250.8 mm in the 24 hours to 9am on the 31st. This is the heaviest August daily rainfall total recorded in Tasmania. Several other sites also received record-breaking daily rainfalls. The heavy rain at in the last two days of the month caused major flooding in the Meander and North Esk Rivers, moderate flooding in the Mersey and upper South Esk rivers, and very strong flows in many other northern rivers. It also ensured that many sites in the north received over 200 mm for the month, and some had their wettest ever August.

Wettest month, wettest overall: Mount Read

The western highlands is one of the wettest parts of Tasmania, and  Mount Read often tops the monthly rainfall bulletins. Although there were many months with below-normal rain in the west December was very wet, with Mount Read receiving 602 millimetres and nearby Lake Margaret Power Station 503 mm. Despite a few days of precipitation missing from the record because of problems with the instruments at such a remote and exposed site, Mount Read registered 4031 mm for the year, the highest of any site in 2005. It is likely that there are other spots that received more rain, but we cannot be certain.
The extraordinary one-day fall at the end of August ensured Breona was the wettest spot in August (and had the second-wettest month overall), with 567 mm for the month.

Driest overall: 459 mm at Hamilton

Over a whole year, it is often the Midlands and the Derwent Valley that are the driest parts of Tasmania, frequently "missing out" on the heavier rain that affects the coasts and the highlands. Hamilton (Clyde River) recorded 459.4 mm of rain for the whole year, although it is possible that a lower total will be found as results from more volunteer observers come in during the next few weeks.

Strongest wind gust: 165 km/h on Mount Wellington on 4 November

An intense low pressure system passing close to southern Tasmania from the 3rd to the 4th of November brought storm force northwesterly winds to the south and southeast of the state. Tree limbs and other debris blocked roads and caused power outages. The strongest gust during that event (and the strongest for 2005) was 165 km/h on the summit of Mount Wellington. Maatsuyker Island registered 163 km/h on that day, and Hobart 122 km/h.


Records

A very large number of records were set in individual months, and  a few set for the year as a whole:

Record Highest Annual Mean Maximum Temperature


Mean daily maximum
temperature
for 2005 (°C)
Previous highest
for
Years of
record
Swansea Post Office 18.7 = 18.7
in 1982
47
Hobart Airport 18.3 18.2
in 1993
46
Eddystone Point 18.1 = 18.1
in 2001
44
Mount Wellington 9.1 8.4
in 2000
21


Record Lowest Daily Maximum Temperature


Lowest daily maximum
temperature
in 2005 (°C)
Previous lowest
for
Years of
record
Maatsuyker Island Lighthouse 5.0
on 10th Aug
= 5.0
on 28th Jun 1983
64
Mount Wellington -5.0
on 11th Aug
= -5.0
on 5th Sep 1995
21

Record Highest Annual Mean Daily Minimum Temperature


Mean daily minimum
temperature
for 2005 (°C)
Previous highest
for
Years of
record
Cape Bruny Lighthouse 9.8 = 9.8
in 1988
73
Grove 6.8 6.7
in 1980
46
Strathgordon Village 6.9 = 6.9
in 1980
29

Two sites had their wettest year since 1975: Launceston Airport Comparison (808.7 mm) and Oatlands Post Office (655.4 mm), and Scamander (815.4 mm) had its wettest year since 1978.

Month by month

Here are links to statements covering the individual months of the year:
January started off quite cool, but the final week was especially warm with temperatures into the 30s. There were several outbreaks of thunderstorms, but total rainfall was below normal in most areas.

Most of February's rain was concentrated in the first week, as a low pressure system close to the state caused very heavy rain in the northeast on the 2nd, and then the southeast on the 3rd.

In March, temperature and rainfall were mostly well below normal, with many sites in the north and the Derwent Valley registering less than 10 mm for the whole month. Liawenee recorded –6.9 °C on the morning of the 26th, the lowest temperature ever recorded in March in Tasmania, and the second-lowest recorded in Australia.

April was actually warmer than March, and Campania's  32.0 °C on the 1st was a new record for the highest Tasmanian April temperature. Rain was close to normal in most areas, and there were many windy days.

In May, very dry conditions persisted in northern, northeastern and Midlands districts, but totals were well above normal in the west. Hobart set a new record for high May minimum (overnight) temperature on the 4th.

Days in June were mostly warmer than normal, and Launceston had its warmest-ever June day on the 10th. There were several cold and frosty nights, and fog was common. Rainfall was well down on normal in the west.

July was warmer than normal across the state, with several monthly records broken. Rain was above normal on Flinders Island and in the western highlands, but below normal near King Island and in the east. Strong and gusty winds were common, especially in the second half of the month. The final week was rather wet in the north; a sign of things to come.

August showed extraordinary variability: a cold outbreak brought snow to sea level (and record cold days) on the 10th and 11th, but in the last week some sites had a record warm day.  On the 30th Grove recorded the highest-ever Tasmanian August minimum temperature. There was also flooding rain in the north, with record daily totals on the 31st (including a new Tasmanian August daily record of 250.8 mm at Breona).

September also brought flooding to the north, along with record wet days in the southeast, but the west had less rain than normal. Temperatures were above normal, with few cold days and many mild nights.

There was more wet weather in October and several places on the East Coast and in the Devonport area had their wettest-ever October. Many sites had their wettest-ever October day. Temperatures were again above normal, especially overnight, with several records set.

November started off very warm, and Flinders Island Airport registered the highest Tasmanian November minimum temperature on the 3rd. There were several significant rainfall events (and a number of thunderstorms), and much of the state was wetter than normal.

December was another warm, wet and windy month. Records were set for high minimum temperatures and high rainfall, with persistent westerly winds that were more typical of spring than summer.

Summary statistics for 2005


Maximum temperatures
for
(°C)
Minimum temperatures
for
(°C)
Rainfall
for
(mm)
Mean for 2005 Difference from normal Highest for 2005 Mean for 2005 Difference from normal Lowest for 2005 Total for 2005 Normal total Ranking
Hobart 17.6 +0.7 36.6 9.2 +0.9 1.1 669 619 normal
Launceston 18.5 +0.2 30.6 7.6 +0.4 -3.1 749 684 high
Burnie 17.4 +0.6 26.3 10.1 +0.8 0.2 1018 972 normal
Devonport
17.1 +0.4 25.8 8.8 +0.8 -0.6 845 788 normal
Swansea 18.7 +0.9 33.6 8.3 +0.6 -1.4 621 597 normal
Strahan
16.7 +0.3 32.9 8.5 +0.7 -1.6 1585 1528 normal
Strathgordon
14.4 +0.5 30.4 6.9 +0.6 -1.4 2750 2526 high
King Island Airport 17.2
33.7 10.1
0.0 796 863 low
Flinders Island Airport 18.2 +0.6 32.9 10.6 +0.9 0.2 649 751 low
Bicheno 18.5 +0.8 32.2 9.7 +0.3 1.4 668 682 normal
Bridport 17.4 -0.1 26.5 9.4 +0.4 -1.0 804 759 normal
Bull Bay 17.3 +0.5 33.0 9.2 +0.3 0.0 596 615 normal
Bushy Park 18.5 +0.9 36.8 6.1 +0.1 -4.1 611 578 normal
Campania 18.8
36.0 7.6
-2.5


Cape Bruny 16.1
35.2 9.5
1.5 764

Cape Bruny Lighthouse 15.8 +1.0 34.2 9.8 +1.1 1.6 928 947 normal
Cape Grim
16.1 +0.5 25.0 10.7 +0.1 3.0 691 732 normal
Cressy 18.0
32.0 6.2
-6.5 883

Dover 17.0 +0.7 36.4 7.6 +0.7 -0.6 847 882 normal
Eddystone Point 18.1 +1.1 30.1 10.7 +0.3 0.8 639 771 low
Fingal 17.9 +0.2 32.2 5.5 +0.3 -5.9 632 610 normal
Friendly Beaches 18.7
33.1 9.6
0.7


Geeveston 17.2 +0.5 35.2 7.2 +1.2 -3.2 896 877 normal
Grove 17.8 +0.7 35.5 6.8 +1.0 -2.7 800 750 normal
Grove 17.6
35.9 6.4
-3.3 813

Hartz Mountain 11.6
30.8 4.3
-4.4


Hobart Airport 18.3 +0.9 35.9 8.9 +0.9 -0.1 564 503 high
Lake Leake 14.4 +0.6 29.1 4.5 +0.6 -5.7 785 836 normal
Lake St Clair 13.3 +0.4 28.4 3.4 +0.8 -5.6 1999 1907 normal
Launceston Airport 18.1
31.9 6.6
-4.1 747

Launceston Airport Comparison 17.5 +0.5 30.8 6.5 +0.3 -3.7 809 683 high
Liawenee 12.2
26.2 1.9
-8.0 1137

Low Head 16.6
24.2 10.8
2.5 815

Luncheon Hill 15.7
32.4 7.9
-0.7 1534

Maatsuyker Island 14.3 +0.4 30.8 9.3 +0.8 1.3 1080 1237 normal
Maria Island 17.4
31.1 10.4
1.8 581

Marrawah 16.5 +0.5 28.2 9.9 +0.7 2.5 1066 1075 normal
Maydena 16.1 0 33.3 5.9 +0.7 -3.9 1227 1227 normal
Melton Mowbray 17.4
35.0 6.5
-3.6 543

Moogara 14.3 +0.5 32.0 5.6 +0.7 -3.8 874 846 normal
Mount Read 8.7
23.9 2.8
-5.0


Mount Wellington 9.1 +1.6 27.8 2.0 +0.7 -7.4


Orford 17.8 +0.2 31.7 8.3 +0.6 -1.0 727 679 normal
Ouse 18.3
36.3 5.9
-5.0 606

Powranna 17.9 +0.3 32.0 6.7 +0.8 -4.5 668 611 normal
Ross 17.9 +0.5 33.5 6.2 +0.8 -5.7 630 503 high
Scamander 18.2 +0.3 32.5 9.1 +0.3 0.5 815 682 high
Scotts Peak Dam 14.8
33.1 6.4
-2.0


Scottsdale 17.4 +0.1 30.3 7.3 +0.2 -3.8 949 1012 normal
Sheffield 16.2
27.3 7.1
-1.6 1340

Smithton
17.2
27.5 7.9
-1.6 934

St Helens
18.0
30.0 9.0
-0.6 791

Swan Island 17.1
25.8 11.7
2.6


Tarraleah
14.4 +0.7 30.6 4.5 +1.0 -5.0 1243 1174 normal
Tasman Island 14.6
25.4 9.2
-0.2 908

Tunnack 15.3
31.9 5.5
-4.2 751

Warra 13.8
31.4 6.0
-2.2


Wynyard
17.3 +0.6 26.6 7.3 +0.4 -2.4 1187 996 high
Macquarie Island 7.1 +0.5 13.6 3.5 +0.5 -4.3 1248 959 highest

Note

This statement has been prepared based on information available at 9 am on Wednesday 4 January 2006 . Although every effort has been made to check them, it is possible that results will change as new information becomes available.

'Normals' are based on all available years of record, which vary widely from site to site . Sites without normals shown do no have sufficient record for them to be calculated reliably.

The 'Ranking' indicates about where rainfall this time ranks in the climate record for the site.

Climate