Thursday, 1 May 2008 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in April 2008 - extreme wind, then settled, then cold

The 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 close to the state early in the month and a cold burst in the last few days of the month.

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.

Dry 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 average 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.

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
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
Coldest day
Lowest daily maximum temperature
-0.2 °C at Mount Wellington on the 28th
Coldest night
Lowest temperature
-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
Warmest night
Highest daily minimum temperature
15.8 °C at Burnie (Round Hill) on the 9th
Wettest overall
Highest total rainfall
259.8 mm at Mount Read
Driest overall
Lowest total rainfall
5.8 mm at Orford (Aubin Court)
Wettest day
Highest daily rainfall
54.6 mm at Mount Read on the 4th
Highest wind gust
176 km/h at Droughty Hill* on the 2nd
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.


Records

Record lowest total April rainfall
Total rainfall
for April 2008 (mm)
Previous lowest
for April
Years of
record
Normal for
April
Orford (Aubin Court) 5.8 11.7 in 1967 56 58.2

Lowest total April rainfall for at least 20 years
Total rainfall
for April 2008 (mm)
Most recent lower
for April
Years since
lower
Normal for
April
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
Mean daily minimum
temperature
for April 2008 (°C)
Previous lowest
for April
Years of
record
Normal for
April
Bushy Park (Bushy Park Estates) 3.9 = 3.9 in 2006 74 6.2



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 April 2008
Maximum temperatures
for April
(°C)
Minimum temperatures
for April
(°C)
Rainfall
for April
(millimetres)
Mean for
April
2008
Diff
from
normal
Highest for
April
2008
Mean for
April
2008
Diff
from
normal
Lowest for
April
2008
Total for
April
2008
Normal
for
April
Rank of
April
2008
Fraction of
April
normal
Northern (district 91)
Bridport 18.2 0.0 21.0 10th 10.1 +0.9 3.8 28th 34.2 52.0 low 66%
Burnie 17.8 +0.1 21.7 17th 11.2 +1.2 4.2 28th 44.0 74.8 normal 59%
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
Devonport Airport 17.6 +0.1 20.4 10th 8.8 +0.4 0.9 29th 32.8 60.4 low 54%
Launceston 18.9 +0.1 23.2 21st 8.4 +1.0 0.4 29th 36.4 50.8 normal 72%
Launceston Airport 17.9   21.0 9th 7.0   1.2 29th 31.4
Launceston Airport Comparison 17.1 -0.3 20.2 21st 7.1 +0.5 1.1 29th 34.8 54.2 normal 64%
Low Head 17.5 -0.2 20.5 10th 11.1 +0.3 5.5 29th 21.0 51.6 low 41%
Luncheon Hill 15.5 0.0 20.7 10th 7.5 -0.4 0.5 30th 109.8 100.3 normal 109%
Marrawah 16.8 0.0 19.4 11th 9.9 -0.3 4.8 28th 62.2 85.4 normal 73%
Powranna 17.6 -0.1 21.5 21st 6.6 +0.6 -0.5 28th 33.2 43.7 normal 76%
Scottsdale 17.3 -0.8 20.9 10th 8.2 +0.3 1.4 29th 52.6 80.0 low 66%
Sheffield School Farm 15.7 -0.9 20.4 21st 7.3 +0.5 0.9 28th 76.0 58.2 normal 131%
Smithton Aerodrome 18.1 +0.5 20.9 21st 7.9 +0.5 -0.5 28th 50.6 55.7 normal 91%
Wynyard Airport 18.1 +0.7 21.9 17th 7.9 +0.9 -0.6 29th 58.0 73.7 normal 79%
East Coast (district 92)
Bicheno 18.3 -0.5 21.8 12th 10.0 -0.2 5.9 1st 9.0 60.0 very low 15%
Eddystone Point 18.5 +0.5 20.9 5th 11.4 0.0 6.5 29th 24.2 65.0 low 37%
Fingal 17.7 -0.6 21.4 17th 5.0 -0.4 -1.7 30th 17.8 52.1 low 34%
Friendly Beaches 18.3 -0.3 23.2 2nd 9.4 -0.2 2.7 30th 10.4 52.3 low 20%
Lake Leake 14.4 +0.3 18.9 11th 2.8 -1.3 -2.4 28th 31.4 70.0 low 45%
Maria Island 17.5   22.2 4th 10.7   7.2 28th 9.8
Orford 18.5 +0.1 25.2 9th 8.0 -0.3 1.8 28th 5.8 58.2 lowest 10%
Scamander 18.1 -0.8 22.5 2nd 9.9 +0.2 3.1 29th 25.2 67.6 low 37%
St Helens Aerodrome 17.9   22.1 2nd 9.7   3.9 30th 30.0
Swan Island 17.8   21.1 25th 12.4   6.2 29th 28.8
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)
Ross 17.8 +0.5 21.2 17th 5.2 -0.4 -2.2 29th 22.0 37.6 low 59%
Southeast (district 94)
Bull Bay 17.0 -0.2 24.0 9th 9.2 -0.2 5.3 28th 26.0 46.6 normal 56%
Campania 18.8   24.7 9th 6.2   1.6 28th 8.2
Cape Bruny 16.3 0.0 22.7 9th 9.3 -0.5 6.6 4th 42.0 52.1 low 81%
Cape Bruny Lighthouse 15.8 +0.3 22.1 9th 9.1 -0.5 4.6 29th 53.2 80.2 low 66%
Dover 16.5 -0.2 23.6 9th 5.7 -1.4 2.0 23rd 37.0 66.8 low 55%
Geeveston 17.3 +0.1 23.8 9th 5.4 -0.8 0.0 11th 41.2 62.8 low 66%
Grove 18.0 +0.5 23.8 9th 4.8 -1.4 1.0 23rd 18.8 61.4 very low 31%
Grove 17.7   23.5 9th 3.9   -1.5 30th 20.0
Hobart 18.0 +0.8 24.4 9th 8.3 -0.6 4.8 28th 19.6 51.2 low 38%
Hobart Airport 18.0 -0.1 24.5 9th 7.8 -0.9 2.6 28th 13.0 43.0 low 30%
Maatsuyker Island Lighthouse 14.4 -0.1 20.7 11th 9.6 +0.2 6.4 29th 61.2 108.9 low 56%
Melton Mowbray 17.4 +0.2 22.4 9th 5.3 -0.2 -0.4 30th 15.4 29.0 normal 53%
Mount Wellington 8.5 +0.2 14.5 9th 1.5 -0.6 -3.0 28th
Tasman Island 14.3   18.7 12th 9.1   5.3 1st 44.0
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)
Bushy Park 18.6 +0.7 24.6 9th 3.9 -2.3 -1.1 30th
Maydena Post Office 15.7 -0.2 21.5 9th 5.4 +0.1 1.8 7th 38.8 85.7 low 45%
Moogara 14.3 +0.5 20.0 9th 4.8 -0.6 0.5 28th 31.6 59.3 low 53%
Ouse Fire Station 18.1 -0.1 23.6 9th 3.7 -0.9 -1.6 30th 24.8
Tarraleah Village 14.1 +0.2 18.8 9th 4.0 0.0 0.1 28th 56.1 95.6 low 59%
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%
Liawenee 11.4   15.6 21st 1.2   -4.6 30th 92.4
West Coast (district 97)
Hartz Mountain 11.4 +0.6 18.8 9th 4.0 -0.2 -0.2 28th 38.2 63.2 low 60%
Mount Read 8.5 -0.4 12.3 18th 3.2 +0.1 -2.1 28th 259.8 257.1 normal 101%
Scotts Peak Dam 14.6 +0.2 22.9 9th 6.1 -0.4 2.5 28th 113.2 117.8 normal 96%
Strahan Aerodrome 16.9 +0.4 23.0 11th 8.0 -0.3 2.3 28th 111.4 111.9 normal 100%
Strathgordon Village 13.8 -0.3 21.5 9th 6.1 -0.8 1.6 28th 132.1 202.5 low 65%
Warra 13.1   19.4 9th 5.3   1.5 29th 77.6
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%
Hogan Island 17.8   20.5 2nd 12.6   7.7 28th 31.0
Macquarie Island (district 300)
Macquarie Island 7.2 +0.3 9.7 3rd 4.2 +0.5 -0.5 22nd 112.8 93.8 high 120%

Notes

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 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 "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