Thursday, 1 May 2008 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0
weather in Tasmania during April 2008 was mostly settled, under the
influence of high pressure systems, leading to rainfall that was below
average in most areas (and very much below average on the East Coast).
However, the most significant events
were destructive winds from a very deep low pressure system
the state early in the month and a cold burst in the last few days of
An archive of previous monthly summaries for Tasmania is also available, as are summaries for other states and many other climate summaries and diagnostics.
Hurricane-force winds: A very deep low pressure system passed close to Tasmania bringing with it destructive winds from late on the 2nd until early on the 3rd. Hurricane force winds have an average speed of 64 knots (118 km/h) or greater: Maatsuyker Island was averaging around 130 km/h from 1:30 am until 3:00 am on the 3rd. Individual gusts well over 100 km/h were recorded at several locations, with the highest being 176 km/h at Droughty Hill* east of Hobart. There were widespread reports of damage, particularly in Hobart's eastern shore suburbs. The atmospheric pressure at Maatsuyker Island dipped to 966.3 hPa, the lowest recorded in Tasmania since November 1994.
Weeks of settled weather: From the 6th to the 9th, and again from the 14th to the 23rd, Tasmania's weather was dominated by high pressure systems close to the state. The result was settled weather and mostly light winds - and very little rain. Temperatures were generally above average by day, as the high was mostly bringing air from the northeast, although there were some cool days in the south and east. Overnight temperatures were mixed through this time, but there were few of the especially cold nights sometimes associated with high pressure systems. Another effect of the high pressure system was the slow dispersal of smoke from vegetation fires.
Only three main rainfall events: The deep low of the 3rd brought rain to most areas, with daily totals over 20 mm common in the north and west; the westerly winds of subsequent days brought further rain to the western highlands. A series of cold fronts from the 9th to the 12th yielded further rain, mostly in the western half. A marked cold change on the 25th and the southerly winds that followed were the third major rain event for the month, giving around 50 mm to the western highlands over three days. The eastern half, and the lower East Coast in particular, missed out on most of the rain from these events, with some sites reporting less than 10 mm for the whole month (Orford had its driest April on record, getting just one-tenth of its April average, whilst Swansea and Bicheno had their driest April for several decades). Overall, rain was below average in most areas, but very much below average on the East Coast and close to average in much of the west and north.
Cold change to finish the month: A cold change late on the 25th saw the month end cool across the state. Daytime temperatures in the low teens were common, with several areas struggling to reach 10 °C. The last three mornings of the month were also quite cold, with sub-zero temperatures reported by several inland sites. Taken across the whole month, maximum (daytime) temperatures were generally above average by about half a degree, but a fraction below average on the south and east coasts. Minimum (overnight) temperatures were generally below average by about half to one degree, except in some of the north where they were above average by a similar amount.
start to the year: The first four months of 2008 have been
relatively dry across most of Tasmania. Only on the northern East Coast
(where there was some very heavy rain in February and local heavy falls in January and March) has rainfall been even close to
so far this year. This situation will be closely monitored, as it
follows a dry 2007 and a record-dry 2006. The Seasonal
Climate Outlook is not giving a strong increase in the chance of it
being wetter than normal in Tasmania over the next three months.
25.5 °C at King Island Airport on the 11th|
|Warmest days on average|
Highest mean daily maximum temperature
|18.9 °C at
Launceston (Ti Tree Bend)|
|Coolest days on average|
Lowest mean daily maximum temperature
8.5 °C at Mount Read and Mount Wellington|
Lowest daily maximum temperature
-0.2 °C at Mount Wellington on the 28th|
-4.6 °C at Liawenee on the 30th|
|Coolest nights on average|
Lowest mean daily minimum temperature
1.2 °C at Liawenee|
|Warmest nights on average|
Highest mean daily minimum temperature
12.6 °C at Hogan Island|
Highest daily minimum temperature
15.8 °C at Burnie (Round Hill) on the 9th|
Highest total rainfall
259.8 mm at Mount Read|
Lowest total rainfall
5.8 mm at Orford (Aubin Court)|
Highest daily rainfall
54.6 mm at Mount Read on the 4th|
|Highest wind gust||176
km/h at Droughty Hill* on
169 km/h at Maatsuyker Island Lighthouse on the 2nd
* Note: The wind recording equipment at the CSIRO-run Droughty Hill TERSS site is not the same as that at Bureau of Meteorology Automatic Weather Stations. However, the peak gust reported appears reasonable. The 169 km/h from Maatsuyker Island is the peak gust from standard equipment.
|Record lowest total April rainfall|
for April 2008 (mm)
|Orford (Aubin Court)||5.8||11.7||in 1967||56||58.2|
|Lowest total April rainfall for at least 20 years|
for April 2008 (mm)
|Most recent lower
|Bicheno (Council Depot)||9.0||0.3||in 1967||34||60.0|
|Swansea Post Office||12.0||10.0||in 1979||29||51.3|
|Record lowest April mean daily minimum temperature|
for April 2008 (°C)
|Bushy Park (Bushy Park Estates)||3.9||= 3.9||in 2006||74||6.2|
|Summary statistics for April 2008|
|Northern (district 91)|
|Cape Grim BAPS||16.9||+0.5||21.5||11th||11.3||0.0||7.0||28th||47.6||66.1||normal||72%|
|Cressy Research Station||17.7||-0.5||20.9||17th||5.6||+0.3||-1.5||30th||53.0|
|Launceston Airport Comparison||17.1||-0.3||20.2||21st||7.1||+0.5||1.1||29th||34.8||54.2||normal||64%|
|Sheffield School Farm||15.7||-0.9||20.4||21st||7.3||+0.5||0.9||28th||76.0||58.2||normal||131%|
|East Coast (district 92)|
|St Helens Aerodrome||17.9||22.1||2nd||9.7||3.9||30th||30.0|
|Swansea Post Office||18.6||-0.1||23.0||25th||7.7||-0.6||2.7||30th||12.0||51.3||low||23%|
|Midlands (district 93)|
|Southeast (district 94)|
|Cape Bruny Lighthouse||15.8||+0.3||22.1||9th||9.1||-0.5||4.6||29th||53.2||80.2||low||66%|
|Maatsuyker Island Lighthouse||14.4||-0.1||20.7||11th||9.6||+0.2||6.4||29th||61.2||108.9||low||56%|
|Tunnack Fire Station||15.4||+0.2||19.5||9th||4.6||-0.4||-1.4||6th||15.6||42.9||low||36%|
|Derwent Valley (district 95)|
|Maydena Post Office||15.7||-0.2||21.5||9th||5.4||+0.1||1.8||7th||38.8||85.7||low||45%|
|Ouse Fire Station||18.1||-0.1||23.6||9th||3.7||-0.9||-1.6||30th||24.8|
|Central Plateau (district 96)|
|Lake St Clair National Park||13.2||+0.2||17.2||7th||2.2||-0.4||-2.5||20th||112.2||136.0||normal||83%|
|West Coast (district 97)|
|Scotts Peak Dam||14.6||+0.2||22.9||9th||6.1||-0.4||2.5||28th||113.2||117.8||normal||96%|
|King Island (district 98)|
|King Island Airport||18.0||+0.5||25.5||11th||10.2||-0.1||5.7||28th||48.8||55.9||normal||87%|
|Flinders Island (district 99)|
|Flinders Island Airport||18.5||-0.2||23.6||11th||9.3||-1.5||4.2||30th||24.4||59.1||low||41%|
|Macquarie Island (district 300)|
This statement has been prepared based on information available at 10 am on Thursday 1 May 2008. Some 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
from all available years of record, which vary widely from site to
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 "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.