Wednesday, 1 April 2009 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0

Tasmania in March 2009: autumn arrives

A number of rainfall events during March meant it was a wetter than average month. This, combined with temperatures that ranged widely (but were never exceptionally hot nor exceptionally cold) and the inevitable lessening of hours of daylight at this time of year, meant the month had a definite a "start of autumn" feel in Tasmania.

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

Rain from the 14th to the 16th: A complex area of low pressure near Tasmania brought rainfalls across the state from the 14th to the 16th. Almost the whole state received over 20 mm, and totals in excess of 50 mm were common in the west, the southeast and parts of the north. Some places received more rain over these three days than is usually expected for all of March. Along with the general rain, a line of thunderstorms resulted in many locally heavy falls as they moved across the state on the 14th. Hobart Airport's rainfall of 22 mm in the 30 minutes to 3 pm reached an intensity expected only once every 50 years. Cape Grim recorded 29.6 mm in the 24 hours to 9 am on the 16th, which is its highest March daily rainfall on record. Flash flooding and other water damage resulted in dozens of insurance claims being lodged.

Above average rainfall: There were a number of other rainfall events during the month which led to a wetter than usual March for nearly all of the state. A cold front on the 3rd and associated low pressure system near southern Tasmania on the 4th spread rain across the state with totals exceeding 30 mm near the Great Western Tiers and nearing 100 mm in the western highlands. This was followed by the statewide rain around the 14th, and then moderate totals in the west and south with a trough on the 22nd, and in the north and west with a trough and cold front on the 25th and 26th. Some sites received twice their usual March rain, and Cape Grim had its wettest March on record. In the north, most sites had their wettest March since 2001, and some sites had their wettest March in over 20 years. Most of the southeast had its wettest March since 2003. February was also wet (except in the north); for many sites in the southeast this is the first time they have had two consecutive "wet" months since the end of 2005.

Warm nights: There was cloud, rain or high humidity on most nights in March so minimum temperatures were generally warmer than usual, especially in the eastern half of the state and on the northwest coast. In the north, nights were quite cool from the 5th to the 8th, but these were more than balanced by several runs of very warm nights. Mean minima for the month were slightly warmer than usual in the west, but one or two degrees warmer than usual for most of the the east. Only two nights at Ross fell below their long term March average, leading to a mean monthly minimum over 3 degrees above normal. Fingal had its highest March mean daily minimum temperature on record, and some other sites in the east had their highest March mean daily minimum temperature for at least 20 years. There were no extremely cold nights, and the coldest temperature recorded at most eastern locations was two or three degrees warmer than is typical for this time of the year. The only reports of sub-zero temperatures during the month were from the mountain-top sites of Mount Wellington and Mount Read; it is unusual for there to be so few especially cold nights in Tasmania during March.

Warm and cool days: There were alternating runs of warm and cool days in March with the passage of high pressure systems and cold fronts. The coldest periods were from the 4th to 7th (in a southerly airflow behind a cold front which brought snow to the highest peaks), on the 15th (in a cold airmass with areas of rain) and on the 30th and 31st (in easterlies). Both Dover and Ouse almost had their coldest March day on record: Dover with 11.9 °C on the 5th and Ouse with 13.0°C on the 30th. Ouse also recorded the hottest days of the month, reaching 30.4°C on the 13th and 30.5°C on the 21st, both days when high pressure systems over the Tasman Sea and approaching cold fronts directed a northerly airflow over the state. There were no extremely hot days, and monthly mean maxima were mostly below average by a few tenths of a degree, but slightly above average at a few sites in the north and east. Many sites had their coolest March since 2005, and at Marrawah it was the coolest March since 1997.

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
30.5°C at Ouse Fire Station on the 21st
Warmest days on average
Highest mean daily maximum temperature
22.7°C at Launceston (Ti Tree Bend)
Coolest days on average
Lowest mean daily maximum temperature
10.9°C at Mount Wellington
Coldest day
Lowest daily maximum temperature
2.1°C at Mount Wellington on the 5th
Coldest night
Lowest temperature
−0.7°C at Mount Wellington on the 6th
Coolest nights on average
Lowest mean daily minimum temperature
4.0°C at Mount Wellington
Warmest nights on average
Highest mean daily minimum temperature
14.1°C at Swan Island
Warmest night
Highest daily minimum temperature
19.7°C at Flinders Island Airport on the 22nd
Wettest overall
Highest total rainfall
312.0 mm at Mount Read
Driest overall
Lowest total rainfall
26.0 mm at Ross (Macquarie River)
Wettest day
Highest daily rainfall
82.4 mm at Mount Read on the 16th
Highest wind gust
135 km/h at Cape Grim BAPS on the 4th

Records

Record highest March daily rainfall
Highest daily rainfall
in March 2009 (mm)
Previous highest
for March
Years of
record
Cape Grim BAPS 29.6 on the 16th 25.0 on the 16th in 2006 22



Record highest total March rainfall
Total rainfall
for March 2009 (mm)
Previous highest
for March
Years of
record
Average for
March
Cape Grim BAPS 72.0 68.8 in 1991 22 38.8

Note that although this site has 21 years of record, the rain gauge was moved in late 2005 and is now likely to record more rain than at its previous location.

Highest total March rainfall for at least 20 years
Total rainfall
for March 2009 (mm)
Most recent higher
for March
Years since
higher
Average for
March
Irishtown 113.2 143.4 in 1977 27 63.6
Launceston Airport Comparison 70.0 87.6 in 1984 25 38.1
Pioneer (Main Road) 98.8 138.2 in 1984 25 57.2
Ringarooma (Fry Street) 118.2 169.0 in 1984 25 64.0
Scottsdale (West Minstone Road) 100.6 135.0 in 1984 25 51.9


Record highest March mean daily minimum temperature
Mean daily minimum
temperature
for March 2009 (°C)
Previous highest
for March
Years of
record
Average for
March
Fingal (Legge Street) 9.8 9.3 in 1999 22 7.8

Highest March mean daily minimum temperature for at least 20 years
Mean daily minimum
temperature
for March 2009 (°C)
Most recent higher
for March
Years since
higher
Average for
March
Grove (Comparison) 9.4 9.6 in 1977 29 7.9
Launceston Airport Comparison 10.6 10.7 in 1985 24 8.9
Launceston (Ti Tree Bend) 11.7 12.1 in 1985 21 10.0



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 March 2009
Maximum temperatures
for March
(°C)
Minimum temperatures
for March
(°C)
Rainfall
for March
(millimetres)
Mean for
March
2009
Diff
from
average
Highest for
March
2009
Mean for
March
2009
Diff
from
average
Lowest for
March
2009
Total for
March
2009
Average
for
March
Rank of
March
2009
Fraction of
March
average
Northern (district 91)
Bridport 20.5 −0.5 25.0 22nd 12.2 +0.8 6.1 6th 78.0 38.4 high 203%
Burnie 20.1 +0.1 24.6 1st 12.9 +1.0 7.6 5th 60.2 49.7 average 121%
Cape Grim BAPS 17.6 −0.9 21.1 10th 12.6 −0.2 8.9 5th 72.0 38.8 highest 186%
Cressy Research Station 22.5   28.1 21st 10.6   2.7 6th 31.6
Devonport Airport 20.5 +0.2 25.3 22nd 12.1 +1.5 4.3 6th 31.2 45.5 average 69%
Launceston 22.7 +0.3 27.2 22nd 11.7 +1.7 5.0 8th 50.6 33.4 high 151%
Launceston Airport 21.9   27.3 21st 10.4   4.0 27th 71.4
Launceston Airport Comparison 21.0 −0.1 26.4 21st 10.6 +1.7 4.2 8th 70.0 38.1 high 184%
Low Head 19.6 −0.2 23.8 22nd 13.7 +0.7 8.4 6th 55.6 33.5 high 166%
Luncheon Hill 18.1 −0.6 25.0 21st 9.8 +0.3 5.2 5th 109.0 80.5 high 135%
Marrawah 18.3 −1.1 22.7 21st 11.6 0.0 8.5 24th 85.0 63.2 high 134%
Scottsdale 21.0 −0.3 25.8 13th 10.7 +0.9 4.6 27th 100.6 51.9 high 194%
Sheffield School Farm 20.1 +0.2 25.1 21st 9.6 +0.4 2.9 29th 73.8 40.4 high 183%
Smithton Aerodrome 19.5 −0.8 22.7 1st 10.2 +1.0 3.0 29th 71.2 41.8 high 170%
Wynyard Airport 20.1 +0.1 24.3 22nd 10.6 +1.3 3.7 6th 76.4 43.0 high 178%
East Coast (district 92)
Bicheno 20.6 +0.1 27.7 19th 13.0 +1.0 8.5 27th 35.0 56.2 average 62%
Eddystone Point 20.9 +0.6 24.5 19th 13.2 −0.1 7.6 5th 56.0 57.4 average 98%
Fingal 21.3 −0.2 30.2 21st 9.8 +2.0 2.7 27th 38.6 44.1 average 88%
Friendly Beaches 21.0 −0.5 28.1 19th 12.5 +0.7 9.1 7th 39.0 53.7 average 73%
Lake Leake 17.4 0.0 25.6 21st 7.3 +1.4 3.2 27th 50.6 62.1 average 81%
Maria Island 19.7   24.2 13th 13.0   9.7 5th 34.4
Orford 20.3 −0.3 25.7 28th 12.2 +1.6 9.1 27th 42.7 44.7 average 96%
Scamander 20.7 0.0 27.9 29th 12.3 +0.5 7.3 8th 34.2 63.2 average 54%
St Helens Aerodrome 20.5   26.3 29th 12.1   6.3 27th 42.8
Swan Island 19.5   22.2 21st 14.1   9.9 6th 70.2
Swansea Post Office 20.7 −0.2 30.0 21st 11.4 +1.1 6.0 8th 32.0 50.4 average 63%
Midlands (district 93)
Ross 21.7 +0.1 28.7 13th 10.8 +3.1 5.5 27th 28.8 30.7 average 94%
Southeast (district 94)
Bull Bay 19.7 0.0 25.0 19th 11.8 +0.5 8.8 5th 108.6 44.7 very high 243%
Campania 21.4   30.1 21st 11.3   7.6 9th 47.4
Cape Bruny 18.5 +0.1 24.3 21st 11.7 +0.2 8.7 5th 95.6 56.0 high 171%
Cape Bruny Lighthouse 17.8 +0.3 23.5 3rd 11.6 +0.5 7.1 27th 99.4 68.6 high 145%
Dover     25.5 3rd 9.0 0.0 4.5 8th 92.4 64.6 high 143%
Geeveston 19.6 −0.5 28.2 21st 9.4 +1.1 5.1 9th 87.8 54.8 high 160%
Grove 20.2 −0.2 29.7 21st 9.4 +1.5 5.7 9th 78.0 48.0 high 163%
Grove 20.0   29.2 21st 9.0   4.8 9th 84.0
Hobart 20.0 −0.1 26.5 19th 12.1 +1.2 8.2 9th 70.2 45.2 high 155%
Hobart Airport 20.5 −0.2 26.1 28th 12.1 +1.4 8.0 9th 59.6 36.6 high 163%
Maatsuyker Island Lighthouse 15.9 −0.4 23.5 3rd 10.8 +0.2 7.1 4th 99.8 85.3 average 117%
Melton Mowbray 20.3 −0.5 30.3 21st 9.7 +1.8 5.7 9th 52.6 33.5 high 157%
Mount Wellington 10.9 −0.4 19.8 21st 4.0 0.0 −0.7 6th 130.2 74.2 high 175%
Tasman Island 16.9   22.8 13th 11.2   8.0 5th 61.4
Tunnack Fire Station 18.0 −1.1 25.0 21st 8.7 +1.4 5.6 9th 77.8 51.7 average 150%
Derwent Valley (district 95)
Bushy Park 21.5 −0.2 29.8 13th 8.9 +0.5 4.3 10th 54.6 39.3 high 139%
Maydena Post Office 18.7 −0.7 28.5 21st 8.0 +1.1 3.5 9th 78.9 69.8 average 113%
Ouse Fire Station 21.2 −1.1 30.5 21st 8.7 +1.1 2.9 10th 60.8 29.2 very high 208%
Tarraleah Village 16.7 −0.7 25.6 21st 6.5 +0.8 3.2 9th 88.0 70.5 average 125%
Central Plateau (district 96)
Butlers Gorge 16.2 −0.4 24.9 21st 5.5 +0.4 0.8 9th 141.4 98.9 high 143%
Lake St Clair National Park 16.0 −0.5 24.2 21st 4.9 +0.9 1.3 9th 138.0 106.2 high 130%
Liawenee 15.7   22.6 21st 4.8   0.0 18th 63.6
West Coast (district 97)
Hartz Mountain 14.0 −0.4 24.3 21st 6.0 0.0 2.1 5th 98.4 68.8 high 143%
Mount Read 11.2 −0.5 20.8 21st 5.0 +0.2 −0.1 5th 312.0 256.9 high 121%
Scotts Peak Dam 17.7 −0.6 28.1 13th 8.1 −0.1 5.2 2nd 138.2
Strahan Aerodrome 18.7 −0.6 27.8 21st 9.6 0.0 4.5 10th 145.2 102.9 high 141%
Strathgordon Village 16.5 −0.9 25.5 21st     5.0 2nd 153.0 146.5 average 104%
Warra 16.1   25.5 21st 7.5   3.0 9th 122.0
King Island (district 98)
King Island Airport 19.4 −0.6 29.8 21st 11.9 0.0 5.1 24th 68.4 49.6 high 138%
Flinders Island (district 99)
Flinders Island Airport 21.3 +0.1 30.2 21st 12.4 −0.1 3.8 6th 57.8 49.9 high 116%
Hogan Island 19.7   25.8 22nd 14.0   10.1 5th 47.0
Antarctica and Macquarie Island (district 300)
Macquarie Island 8.0 +0.1 9.7 3rd 5.0 +0.3 1.8 30th 115.8 99.2 high 117%

Notes

This statement has been prepared based on information available at 10 am on Wednesday 1 April 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