Monday, 1 June 2009 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in May 2009: Wet in the west and dry in the east

Several cold fronts crossed the state in May, delivering over 500 mm of rain to Mount Read. In contrast, several sites in the east received less than 10 mm. Night time temperatures ranged from very cold to very warm, but days were mostly near or slightly warmer than usual until the end 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.

Details

Wet in the west and dry in the east: A westerly airstream with several cold fronts ensured that most of the rain in May fell in the west, and resulted in a stark contrast between the highest rainfall (over 500 mm at Mount Read) and the lowest (just 6 mm at St Helens). Monthly totals for some sites in the central east and northeast were less than 10 mm (although it is not uncommon to have such a dry month there; similar May totals have typically occurred once every five or so years). The heaviest rain fell with cold fronts on the 14th and 15th. Mount Read received 140.6 mm in the 24 hours to 9 am on the 15th, its highest daily total since records began there in 1996, and 232.2 mm over the two days, also a record. For the whole month, it was drier than usual in the east, central north, Bass Strait and on the west coast but rainfall was near or above average over the remainder.

Some very cold nights, and some very warm: Minimum temperatures during the month varied widely. The coldest temperature was −5.2°C, recorded at Liawenee on the 5th and Lake Leake on the 20th. Several other sites had sub-zero temperatures on these nights and also on the 18th and 19th, with very frosty conditions were reported around Ross and Cressy. In contrast, many overnight temperatures remained in the mid-teens between the 24th and 26th. Minima were up to ten degrees above average and several sites in the north and west had their warmest May night in over ten years. Tarraleah has its warmest May night on record on the 25th, beating the previous record by almost a degree. Mean minima for the month were mostly slightly above average, but were around a degree warmer than usual at a few sites in the Huon Valley and a little below average at a handful of sites.

No extreme daytime temperatures: The last few days of May were quite cold, and there were a few warm days around the 24th, but otherwise most daytime temperatures in May were near average. Mean maxima for the month were near average in the west, south and Bass Strait but half to one degree above average elsewhere. The last four days were below 15°C in Launceston, but these were the only cold days in a city that would normally have about 11 May days below 15°C; this ensured that Launceston had its warmest mean daily maximum for May. Hobart was also mild until the last four days when there were three days below 12°C; before that there were none. The cold conditions were caused by a slow moving high pressure system over the Bight which directed a cold southerly airflow over the state. 

Wild and windy between the 14th and 17th: Though most of the weather in May was fairly benign, the period between the 14th and 17th was wild, windy and wet in most areas as a series of active cold fronts crossed the state. The first front crossed in the early hours of the 14th, bringing heavy falls to the western highlands, including around 50 mm to upper parts of the Huon River catchment which led to minor flooding in some parts of the Huon River. More heavy rain fell in the west and south on the following days, with plenty of snow on the 15th and 16th falling to as low as 350 metres. On the 16th swells reached over 6 metres on the south coast as a deep low pressure system crossed waters to the south of Tasmania. It was also very windy for the whole period, but especially so early on the 17th when gusts reached 139 km/h at Droughty Hill and 109 km/h in Hobart, causing extensive damage to trees and houses around Lenah Valley and West Hobart and some power outages. Conditions moderated on the 18th as a high pressure system moved near the state.

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
20.6°C at Swansea Post Office on the 8th
Warmest days on average
Highest mean daily maximum temperature
17.4°C at Bicheno (Council Depot)
Coolest days on average
Lowest mean daily maximum temperature
5.7°C at Mount Wellington
Coldest day
Lowest daily maximum temperature
1.0°C at Mount Wellington on the 30th
Coldest night
Lowest temperature
−5.2°C at Liawenee on the 5th and
Lake Leake (Elizabeth River) on the 20th
Coolest nights on average
Lowest mean daily minimum temperature
0.9°C at Liawenee
Warmest nights on average
Highest mean daily minimum temperature
11.6°C at Hogan Island
Warmest night
Highest daily minimum temperature
15.9°C at Bicheno (Council Depot) on the 26th
Wettest overall
Highest total rainfall
528.8 mm at Mount Read
Driest overall
Lowest total rainfall
6.0 mm at St Helens Aerodrome
Wettest day
Highest daily rainfall
140.6 mm at Mount Read on the 15th
Highest wind gust
139 km/h at Cape Grim BAPS on the 16th

Records

Record highest May mean daily maximum temperature
Mean daily maximum
temperature
for May 2009 (°C)
Previous highest
for May
Years of
record
Average for
May
Launceston (Ti Tree Bend) 16.8 16.6 in 2007 27 15.8



Record highest May daily minimum temperature
Highest daily minimum
temperature
in May 2009 (°C)
Previous highest
for May
Years of
record
Average for
May
Tarraleah Village 11.9 on the 25th 11.0 on the 2nd in 1997 26 2.4



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 May 2009
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2009
Diff
from
average
Highest for
May
2009
Mean for
May
2009
Diff
from
average
Lowest for
May
2009
Total for
May
2009
Average
for
May
Rank of
May
2009
Fraction of
May
average
Northern (district 91)
Bridport 16.2 +0.3 18.6 4th 8.2 +0.3 3.5 18th 9.8 65.1 very low 15%
Burnie 16.0 +0.7 19.8 8th 9.4 +1.1 3.8 18th 51.2 94.2 low 54%
Cape Grim BAPS 14.5 −0.2 16.8 11th 10.4 +0.2 6.4 29th 48.8 75.4 average 65%
Cressy Research Station 15.7 +0.9 19.1 8th 3.2 −0.3 −4.7 18th 21.4 39.2 low 55%
Devonport Airport 15.9 +0.6 18.6 23rd 7.7 +0.9 1.1 18th 16.4 74.3 very low 22%
Launceston 16.8 +1.0 19.9 23rd 5.2 +0.1 −0.2 31st 12.8 62.3 very low 21%
Launceston Airport 15.3   18.5 25th 4.3   −1.2 19th 14.0
Launceston Airport Comparison 14.8 +0.8 17.7 25th 4.6 0.0 −1.4 19th 16.4 60.0 low 27%
Low Head 15.5 +0.1 17.8 4th 9.7 +0.2 5.4 18th 10.6 56.6 very low 19%
Luncheon Hill 13.1 +0.1 16.7 21st 7.3 +0.3 3.4 5th 146.2 162.7 average 90%
Marrawah 14.5 −0.3 17.0 24th 9.2 +0.1 5.0 19th 80.2 103.8 low 77%
Scottsdale 15.3 +0.4 18.1 8th 6.0 +0.1 1.6 6th 17.8 99.8 very low 18%
Sheffield School Farm 14.5 +0.9 18.6 8th 5.4 −0.2 0.4 29th 60.0 84.0 low 71%
Smithton Aerodrome 15.4 −0.1 18.0 24th 6.6 +0.3 −1.0 19th 76.8 82.0 average 94%
Wynyard Airport 15.8 +0.8 19.7 8th 6.1 +0.8 −0.6 29th 90.6 99.1 average 91%
East Coast (district 92)
Bicheno 17.4 +0.9 19.8 15th 9.6 +1.2 5.5 5th 12.0 56.0 low 21%
Eddystone Point 17.3 +1.5 19.7 4th 10.2 +0.5 6.4 19th 9.8 66.2 very low 15%
Fingal 15.8 +0.5 19.1 8th 3.1 +0.3 −3.2 5th 8.4 49.8 very low 17%
Friendly Beaches     20.5 8th 8.7 +0.4 2.5 20th
Lake Leake 12.1 +0.7 15.9 21st 1.5 −0.7 −5.2 20th 20.4 73.2 low 28%
Maria Island 15.3   18.7 26th 9.8   5.1 16th 15.0
Orford 15.7 −0.1 19.3 8th 6.3 0.0 1.4 20th 15.2 57.5 low 26%
Scamander 17.1 +0.5 19.7 15th 7.9 +0.3 3.2 17th 9.7 52.9 very low 18%
St Helens Aerodrome 16.9   20.2 8th 7.8   2.4 19th 6.0
Swan Island 16.0   18.3 20th 10.9   6.5 28th 13.0
Swansea Post Office 16.3 +0.3 20.6 8th 6.2 −0.1 0.2 20th 10.4 46.1 low 23%
Midlands (district 93)
Ross 15.1 +0.7 19.1 25th 3.1 −0.3 −3.9 20th 12.2 25.0 average 49%
Southeast (district 94)
Bull Bay 14.8 −0.3 17.5 8th 8.2 +0.1 4.1 16th 41.0 37.8 average 108%
Campania 15.7   19.3 2nd 6.0   −0.5 19th 32.6 27.9 high 117%
Cape Bruny 13.8 −0.6 17.7 23rd 8.8 +0.1 5.0 16th 54.4 51.5 average 106%
Cape Bruny Lighthouse 13.6 +0.1 17.3 23rd 8.6 +0.4 3.3 17th 70.6 84.0 average 84%
Dover 14.4 −0.4 19.4 23rd 6.0 +0.2 0.2 19th 52.0 70.8 average 73%
Geeveston 14.7 +0.1 19.2 23rd 6.1 +1.5 −0.7 19th 86.8 70.7 high 123%
Grove 14.8 +0.2 18.7 24th 5.6 +1.3 −1.8 1st 67.0 59.2 high 113%
Grove 14.6   18.6 24th 5.2   −0.9 1st 71.6
Hobart 15.5 +1.1 19.3 23rd 7.9 +0.9 3.1 19th 54.2 46.5 average 117%
Hobart Airport 15.5 +0.3 19.2 8th 7.2 +0.6 1.8 19th 31.0 34.5 average 90%
Maatsuyker Island Lighthouse 12.7 −0.1 19.1 23rd 9.1 +0.7 4.2 16th 96.0 115.2 average 83%
Melton Mowbray 14.0 −0.3 17.4 23rd 5.2 +0.8 −2.0 20th 27.8 24.8 average 112%
Mount Wellington 5.7 +0.1 10.8 20th 1.0 +0.5 −2.3 14th
Tasman Island 12.7   15.6 3rd 8.4   3.7 16th 59.2
Tunnack Fire Station 12.3 −0.2 15.7 3rd 4.1 +0.4 −1.2 19th 41.4 39.6 average 105%
Derwent Valley (district 95)
Bushy Park 14.8 +0.5 19.4 23rd 4.7 +0.6 −1.3 1st 29.0 45.4 average 64%
Maydena Post Office 13.0 −0.1 17.6 23rd 5.4 +1.1 −0.7 1st 107.4 96.3 average 112%
Ouse Fire Station 14.5 −0.5 18.7 23rd 4.3 +0.5 −1.7 20th 37.8 32.0 high 118%
Tarraleah Village 11.4 +0.3 16.1 21st 3.5 +1.0 −1.7 19th 112.7 102.4 high 110%
Central Plateau (district 96)
Butlers Gorge 10.6 +0.7 15.7 21st 2.6 +0.9 −4.3 20th 160.6 160.5 average 100%
Lake St Clair National Park 10.2 −0.2 14.4 21st 2.0 +0.4 −3.8 19th 179.2 167.7 average 107%
Liawenee 9.4   14.4 19th 0.9   −5.2 5th 43.2
West Coast (district 97)
Hartz Mountain 8.2 −0.5 14.7 21st 3.6 +0.2 −0.7 16th 83.2 70.2 average 119%
Mount Read 6.5 0.0 11.5 20th 2.3 0.0 −1.8 16th 528.8 417.4 high 127%
Scotts Peak Dam 11.7 +0.2 18.0 23rd 5.6 0.0 2.0 19th 161.6
Strahan Aerodrome 14.1 −0.1 19.3 23rd 7.2 −0.2 0.8 30th 133.2 136.4 average 98%
Strathgordon Village 11.4 −0.1 16.8 23rd    
313.9 242.7 high 129%
Warra 11.2   15.6 24th 5.1   1.1 19th 195.8
King Island (district 98)
King Island Airport 15.6 0.0 17.3 24th 9.7 +0.4 3.2 5th 36.0 85.1 very low 42%
Flinders Island (district 99)
Flinders Island Airport 16.3 +0.1 19.1 21st 8.8 −0.2 −0.1 19th 26.0 79.5 very low 33%
Hogan Island 15.4   17.7 24th 11.6   7.3 16th 37.0
Antarctica and Macquarie Island (district 300)
Macquarie Island 6.0 +0.1 7.5 22nd 3.5 +1.0 0.3 8th 56.2 82.9 low 68%


Notes

This statement has been prepared based on information available at 9 am on Monday 1 June 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

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