Friday, 1 May 2009 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in April 2009: warm, windy, wet... then cold to finish

Warm, wet and windy conditions were felt in Tasmania at various times during April, and the last five days were very cold. Daytime temperatures at the end of the month struggled to reach what they had been overnight early in the month, and several records were broken. Destructive winds blew across the north on the 15th, peaking at 194 km/h at Scottsdale (nearly a Tasmanian record). Rainfall for most of the state was near or above normal.

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

Warm at the start: Northerly winds blew across Tasmania during the first few days of the month and temperatures were very warm, reaching into the mid-twenties during the day and staying warm during the night. Most overnight temperatures remained in the mid to high teens. Wynyard's minimum of 17.2°C on the 2nd was its warmest April night on record, but this was broken on the 3rd when it didn't fall below 17.7°C. Several other places had their warmest April night in over 15 years. 

Cold at the end: A southerly change on the 26th brought very cold conditions which persisted for the rest of the month. The lowest April minimum and maximum temperature records at a number of sites were broken, on multiple days at some sites. Daytime temperatures struggled to reach what they has been overnight at the start of the month, and overnight temperatures fell well below zero at many sites. Liawenee's −7.5°C early on the 29th is the second-coldest April temperature ever recorded in Tasmania, and the temperature on Mount Wellington stayed below −1°C on the 27th and 28th; both days are in the coldest five April days ever measured in Tasmania. Hobart had three consecutive days below 12°C - this hasn't happened since 1952 - and Launceston had an unprecedented five days in a row below 15°C. A media release was issued to cover the unseasonably cold weather.

But temperatures close to average overall:  There were a few cold days after fronts crossed the state (on the 6th and 15th) and a warm day on the 14th (ahead of a front), but otherwise temperatures were near normal in the middle part of the month. This meant that mean maxima and minima for April were near normal. Daytime temperatures were generally around half a degree below normal. The warm nights at the start of the month compensated for the cold ones at the end, so overnight temperatures mostly about half a degree warmer than usual.

Damaging winds: Severe thunderstorms on a cold front affected northern areas on the morning of the 15th. Wind gusts of over 100 km/h were common, causing extensive structural and tree damage, particularly at Boat Harbour, Wynyard and Scottsdale, and power outages to around 30,000 premises. The peak gust of 194 km/h at Scottsdale was most likely associated with a tornado, and is the second-strongest wind gust ever recorded in Tasmania (the strongest is 200 km/h on Mount Wellington). A deep low on the 26th also caused damaging winds in some areas. Gusts reached 152 km/h at Hogan Island and Maatsuyker Island, which ranks in the top ten April gusts for Tasmania.

Wet in the north and southeast, otherwise near average rainfall: The main rain events during April were associated with cold fronts and a low pressure system. Fronts on the 15th and 16th brought falls of over 50 mm to the western highlands, 20 to 30 mm to most of the north and 5 to 15 mm elsewhere. This was followed by statewide rain between the 24th and 26th with further fronts and a deep low pressure system which moved across the north coast on the 26th. Heavy rain fell in the north with many sites receiving over 70 mm, many sites in the southeast and west received 30 to 50 mm, and most remaining areas received 10 to 20 mm. The highest three-day total was 100.6 mm at Pipers River, whilst the highest daily total was 72.0 mm at Railton in the 24 hours to 9 am on the 25th. These two events led to a wetter than usual April in the north (some sites, including Ulverstone and Scottsdale, had their wettest April since 1992) and in parts of the southeast. Totals were near average elsewhere, except for a few sites around Bothwell and in the central east which were drier than usual.

A generally wet start to the year: With various areas of the state experiencing average or even above-average rain in JanuaryFebruary or March as well as April, totals for the first four months of the year are mostly near average. The main exception is the East Coast and Flinders Island, where totals are below average so far. Rainfall over the past two months means that some areas (especially in the southeast and the north) have had their wettest start to autumn since at least 2003. However, for most of Tasmania the period since January 2006 ranks as the driest 40 months on record; it will take a great deal of rain to remove these longer-term deficits.

Further information

Melanie Webb
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
26.5°C at Strahan Aerodrome on the 2nd,
and at Friendly Beaches and Swansea on the 3rd
Warmest days on average
Highest mean daily maximum temperature
18.7°C at Bicheno (Council Depot)
Coolest days on average
Lowest mean daily maximum temperature
7.7°C at Mount Wellington
Coldest day
Lowest daily maximum temperature
−1.9°C at Mount Wellington on the 27th
Coldest night
Lowest temperature
−7.5°C at Liawenee on the 29th
Coolest nights on average
Lowest mean daily minimum temperature
1.2°C at Liawenee
Warmest nights on average
Highest mean daily minimum temperature
12.5°C at Hogan Island
Warmest night
Highest daily minimum temperature
18.1°C at Flinders Island Airport on the 2nd
Wettest overall
Highest total rainfall
333.8 mm at Mount Read
Driest overall
Lowest total rainfall
23.6 mm at Ashton (Ouse River)
Wettest day
Highest daily rainfall
72.0 mm at Railton (Dowbiggin Street) on the 25th
Highest wind gust
194 km/h at Scottsdale (West Minstone Road) on the 15th

Records

Record lowest April daily maximum temperature
Lowest daily maximum
temperature
in April 2009 (°C)
Previous lowest
for April
Years of
record
Average for
April
Orford (Aubin Court) 10.0 on the 28th 10.3 on the 22nd in 1969 41 18.4
Scottsdale (West Minstone Road) 9.8 on the 26th 11.0 on the 5th in 1983 37 18.0
Tarraleah Village 5.5 on the 27th 5.8 on the 7th in 2006 25 13.9
Dover 9.6 on the 27th 9.8 on the 6th in 2006 20 16.7
Lake Leake (Elizabeth River) 6.4 on the 28th 6.6 on the 21st in 1999 20 14.1



Record highest April daily minimum temperature
Highest daily minimum
temperature
in April 2009 (°C)
Previous highest
for April
Years of
record
Average for
April
Wynyard Airport 17.7 on the 3rd 16.7 on the 10th in 1961 24 7.0

Macquarie Island also had some record warm nights. Its minimum of 7.8°C on the 15th equalled its previous warmest April night recorded on 19 April 2006. This was then beaten on the 25th, when a minimum of 8.0°C was recorded. (Macquarie Island has 62 years of record).


Record lowest April temperature
Lowest temperature
in April 2009 (°C)
Previous lowest
for April
Years of
record
Average for
April
Flinders Island Airport −0.3 on the 30th 0.1 on the 27th in 1967 47 10.7
Fingal (Legge Street) −4.8 on the 30th −4.6 on the 21st in 1994 23 5.4
Geeveston (Cemetery Road) −2.8 on the 30th −2.5 on the 25th in 1997 23 6.2
Dover −2.0 on the 30th −0.5 on the 17th in 2006 20 7.0
Lake Leake (Elizabeth River) −5.9 on the 29th −4.9 on the 25th in 1997 20 4.1

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 2009
Maximum temperatures
for April
(°C)
Minimum temperatures
for April
(°C)
Rainfall
for April
(millimetres)
Mean for
April
2009
Diff
from
average
Highest for
April
2009
Mean for
April
2009
Diff
from
average
Lowest for
April
2009
Total for
April
2009
Average
for
April
Rank of
April
2009
Fraction of
April
average
Northern (district 91)
Bridport 17.6 −0.5 21.2 2nd 9.7 +0.4 2.2 28th 106.1 56.0 very high 189%
Burnie 17.6 −0.1 21.4 18th 11.0 +1.1 4.0 29th 84.6 75.0 average 113%
Cape Grim BAPS 16.0 −0.4 20.6 14th 11.2 −0.1 4.9 28th 95.8 67.4 high 142%
Cressy Research Station 17.8 −0.3 22.3 14th 5.8 +0.5 −3.7 30th 53.0 43.5 average 122%
Devonport Airport 17.8 +0.2 22.8 18th 9.4 +1.0 1.2 28th 64.0 60.6 average 106%
Launceston 18.4 −0.4 23.9 3rd 7.8 +0.4 −0.6 30th 73.6 51.5 high 143%
Launceston Airport 17.4   23.8 3rd 6.6   −1.3 30th 68.2
Launceston Airport Comparison 16.8 −0.6 22.9 3rd 7.0 +0.4 −1.6 30th 76.2 54.5 high 140%
Low Head 16.9 −0.7 20.1 2nd 11.4 +0.6 3.7 29th 89.4 54.9 very high 163%
Luncheon Hill 15.0 −0.5 20.6 2nd 8.2 +0.3 0.3 28th 144.4 103.4 high 140%
Marrawah 16.3 −0.5 22.0 2nd 10.3 +0.1 3.5 28th 99.0 85.7 high 116%
Scottsdale 16.7 −1.4 21.6 3rd 8.0 +0.1 −0.3 6th 121.6 81.0 high 150%
Sheffield School Farm 16.0 −0.5 20.2 18th 7.3 +0.5 −1.5 29th 108.2 62.4 very high 173%
Smithton Aerodrome 17.2 −0.5 21.9 2nd 8.2 +0.8 −0.7 29th 86.8 58.1 high 149%
Wynyard Airport 17.4 0.0 21.3 18th 8.4 +1.5 −1.1 29th 86.2 74.1 high 116%
East Coast (district 92)
Bicheno 18.7 −0.2 22.0 3rd 10.5 +0.3 3.3 30th 30.4 59.6 low 51%
Eddystone Point 18.5 +0.5 22.8 18th 11.5 +0.1 5.0 6th 48.2 64.9 average 74%
Fingal 17.8 −0.5 25.3 3rd 5.8 +0.4 −4.8 30th 25.8 51.9 average 50%
Friendly Beaches     26.5 3rd 10.3 +0.8 1.5 30th 28.4 50.3 average 56%
Lake Leake 14.1 0.0 22.2 3rd 3.7 −0.3 −5.9 29th 36.4 69.8 low 52%
Maria Island 17.3   21.6 14th 11.2   5.5 30th 57.6
Orford 17.7 −0.6 24.3 3rd 8.5 +0.1 0.5 30th 56.1 58.1 average 97%
Scamander 18.4 −0.4 25.9 3rd 9.8 +0.1 2.2 30th 37.8 66.4 average 57%
St Helens Aerodrome 18.2   26.1 3rd 10.2   1.3 30th 41.8
Swan Island 17.6   21.0 23rd 12.4   6.2 28th 48.2
Swansea Post Office 18.6 −0.1 26.5 3rd 7.7 −0.6 −0.5 30th 27.4 51.1 average 54%
Midlands (district 93)
Ross 17.8 +0.4 23.2 3rd 6.5 +1.0 −4.0 29th 37.4 37.6 average 99%
Southeast (district 94)
Bull Bay 16.6 −0.6 24.0 2nd 9.3 −0.1 2.6 30th 65.6 47.3 high 139%
Campania 18.0   25.0 2nd 7.2   −1.4 30th 36.0
Cape Bruny 15.9 −0.4 23.3 2nd 9.7 0.0 3.7 29th 55.4 52.4 average 106%
Cape Bruny Lighthouse 15.4 0.0 22.8 2nd 9.6 0.0 3.6 29th 75.0 80.2 average 94%
Dover 16.2 −0.4 24.2 2nd 6.4 −0.7 −2.0 30th 83.4 67.1 high 124%
Geeveston 17.0 −0.2 25.0 2nd 6.3 +0.1 −2.8 30th 80.0 63.3 high 126%
Grove 17.7 +0.2 24.7 2nd 7.3 +1.1 0.0 29th 56.8 61.3 average 93%
Grove 17.1   24.1 2nd 6.1   −2.1 30th 65.4
Hobart 17.6 +0.4 24.7 2nd 9.0 +0.1 1.3 30th 66.8 51.3 high 130%
Hobart Airport 17.6 −0.5 25.1 2nd 9.2 +0.4 1.3 30th 48.2 43.1 average 112%
Maatsuyker Island Lighthouse 14.1 −0.3 25.5 2nd 9.7 +0.2 4.6 6th 62.6 108.5 low 58%
Melton Mowbray 16.7 −0.5 23.6 3rd 6.3 +0.8 −3.3 29th 25.4 28.8 average 88%
Mount Wellington 7.7 −0.7 14.5 2nd 1.6 −0.5 −5.6 6th 63.0 85.3 average 74%
Tasman Island 14.2   20.1 2nd 9.3   3.6 6th 106.0
Tunnack Fire Station 14.5 −0.6 20.0 2nd 5.5 +0.6 −4.1 30th 39.6 42.7 average 93%
Derwent Valley (district 95)
Bushy Park 18.0 +0.1 25.3 2nd 5.3 −0.9 −3.5 30th 29.0 46.8 low 62%
Maydena Post Office 15.3 −0.5 23.9 2nd 5.7 +0.4 −1.4 30th 74.7 85.1 average 88%
Ouse Fire Station 17.5 −0.8 25.5 2nd 4.5 0.0 −5.6 30th 25.8
Tarraleah Village 13.7 −0.2 20.8 2nd 4.5 +0.5 −1.7 29th 98.8 95.6 average 103%
Central Plateau (district 96)
Butlers Gorge 13.1 +0.1 21.0 2nd 3.1 −0.2 −4.6 29th 135.2 146.3 average 92%
Lake St Clair National Park 13.0 +0.1 18.7 2nd 3.3 +0.6 −4.4 29th 119.0 135.2 average 88%
Liawenee 11.2   16.5 8th 1.2   −7.5 29th 62.6
West Coast (district 97)
Hartz Mountain 10.7 −0.1 19.2 2nd 4.1 −0.2 −1.6 28th 78.4 64.3 high 122%
Mount Read 8.3 −0.6 16.8 2nd 3.2 0.0 −2.9 28th 333.8 263.5 high 127%
Scotts Peak Dam 14.4 0.0 24.0 2nd 6.4 0.0 −0.4 29th 174.0 122.9 high 142%
Strahan Aerodrome 16.6 +0.1 26.5 2nd 8.3 +0.1 1.2 29th 139.2 113.2 high 123%
Strathgordon Village 13.7 −0.4 21.8 14th 6.4 −0.5 2.1 6th 194.9 202.3 average 96%
Warra 13.0   21.7 2nd 5.5   −2.5 29th 155.4
King Island (district 98)
King Island Airport 17.4 −0.2 25.9 2nd 10.3 +0.1 1.3 29th 73.6 56.7 high 130%
Flinders Island (district 99)
Flinders Island Airport 18.1 −0.6 24.3 3rd 10.3 −0.4 −0.3 30th 49.4 59.0 average 84%
Hogan Island 17.5   22.8 3rd 12.5   7.3 28th 76.0
Antarctica and Macquarie Island (district 300)
Macquarie Island 7.4 +0.5 9.6 2nd 4.4 +0.7 1.4 7th 73.8 93.4 low 79%


Notes

This statement has been prepared based on information available at 9 am on Friday 1 May 2009. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

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

Further information

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