Monday, 1 October 2007 - Monthly Climate Summary for Tasmania - Product code IDCKGC17R0
A burst of westerly winds and several cold fronts near the end of the month meant rainfall totals for September 2007 were close to normal in many parts of the state, but in the east it was yet another in the long series of drier-than-usual months that Tasmania has experienced since the start of 2006. Warm days were more prevalent than cool ones, but there were several quite cold nights.
Some rain, but dry in the east: There were some moderate to heavy falls of rain during the month, particularly as fronts crossed the state around the 2nd, the 24th and particularly over the final four days. Nonetheless, for most of the month most of the state was relatively dry, especially in the east. Totals for the month were below average near the East Coast and the northern Midlands, and well below average on the lower East Coast. South Bruny Island and parts of the inland northwest had totals above the long-term September average. As is often the case when westerly winds bring the rain, there was a stark contrast between the western highlands (with well over 200 mm) and the lower East Coast (with less than 20 mm).
Long-term deficits remain: Despite the recent rain and notable rainfall events during August and May, most of the last 21 months have been much drier than normal across Tasmania. The last extended period of above-average rain was at the end of 2005. To even begin to make up these deficits will require a sustained period of above-average falls. Just one example is Burnie, where the 971 mm recorded over the last 21 months is 735 mm less than the long-term average for the same period. The record wet October-to-December in 2005 provided Burnie with 424 mm, so even a repeat of that extraordinary rain would not remove the current long-term deficit. Similar stories emerge in other parts of the state.
Mild days: There were several warm days during September, notably the 19th when temperatures into the low 20s were reported in the southeast. There were very few particularly cold days, the main exception being the 3rd. The result was mean maximum temperatures above the long-term average across the state, typically by around half a degree in the north and about a degree in the southeast.
Some cold nights: There were several quite cold nights during the month: a very cold morning on the 4th, with another (in most areas) on the 9th, again on the 16th and both the 22nd and 23rd. A number of mild nights (notably the 2nd and 14th) were not enough to counter the colder ones, so mean minimum temperatures were below average in most parts of the state, typically by half a degree, although the northeast and southeast coasts were a little above average.
Less westerly winds than usual — until the end: September is often a time of strong westerly winds across Tasmania, but this month it was only the final week that saw sustained westerly winds and cold fronts. It was rain from that series of fronts that prevented the north and west from having another dry month, but it was accompanied by many gusts well over 100 km/h.
22.4°C at Dover on the 19th|
|Warmest days on average|
Highest mean daily maximum temperature
17.1°C at Friendly Beaches|
|Coolest days on average|
Lowest mean daily maximum temperature
|5.7°C at Mount Read|
Lowest daily maximum temperature
–1.6°C at Mount Wellington on the 3rd|
–6.3°C at Liawenee on the 4th|
|Coolest nights on average|
Lowest mean daily minimum temperature
–0.9°C at Liawenee|
|Warmest nights on average|
Highest mean daily minimum temperature
9.4°C at Swan Island|
Highest daily minimum temperature
13.0°C at Bicheno (Council Depot) on the 14th|
Highest total rainfall
mm at Lake Margaret Power Station|
Lowest total rainfall
|12.8 mm at Swansea Post Office|
Highest daily rainfall
66.8 mm at Zeehan (West Coast Pioneers Museum) on the 30th|
|Highest wind gust||
135 km/h at Hogan Island on the 28th|
and Maatsuyker Island Lighthouse on the 29th
and Scotts Peak Dam on the 29th
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 September 2007|
|Northern (district 91)|
|Cape Grim BAPS||13.7||+0.4||16.4||13th||8.5||0||4.1||4th||92.4||74.3||normal||124%|
|Cressy Research Station||14.6||17.7||12th||3.2||–3.1||23rd||45.6|
|Launceston Airport Comparison||14.3||+0.3||17.4||17th||3.9||–0.4||–2.2||4th||46.8||63.8||low||73%|
|Sheffield School Farm||13.1||0||16.9||25th||4.1||–0.7||–1.8||4th||118.4||136.3||low||87%|
|East Coast (district 92)|
|Friendly Beaches||17.1||+0.5||21.1||18th||7.5||0||2.2||23rd||19.6||34.0||very low||58%|
|St Helens Aerodrome||15.8||18.1||21st||7.1||1.7||23rd||20.0|
|Swansea Post Office||16.9||+0.9||20.9||18th||6.2||+0.4||–1.5||23rd||12.8||40.4||very low||32%|
|Midlands (district 93)|
|Southeast (district 94)|
|Cape Bruny Lighthouse||14.2||+1.0||21.0||19th||7.8||+0.8||4.0||4th||91.6||80.5||high||114%|
|Maatsuyker Island Lighthouse||13.0||+0.9||18.0||23rd||7.8||+1.0||4.7||4th||102.8||109.5||normal||94%|
|Tunnack Fire Station||12.6||0||15.3||7th||2.9||–0.5||–3.6||4th||34.6||55.8||low||62%|
|Derwent Valley (district 95)|
|Maydena Post Office||14.1||+0.4||20.0||19th||2.9||–0.5||–1.5||7th||131.4||136.5||normal||96%|
|Ouse Fire Station||15.7||–0.1||20.5||18th||2.5||–1.4||–4.2||23rd||66.6||73.1||normal||91%|
|Central Plateau (district 96)|
|Lake St Clair National Park||10.8||+0.7||15.2||8th||0.4||–0.3||–4.4||4th||201.8||205.7||normal||98%|
|West Coast (district 97)|
|Scotts Peak Dam||13.5||19.3||13th||4.4||0.1||4th||200.2|
|King Island (district 98)|
|King Island Airport||15.4||+1.0||19.9||23rd||8.3||+0.1||1.1||22nd||68.2||87.5||normal||78%|
|Flinders Island (district 99)|
|Flinders Island Airport||15.3||+0.3||18.3||19th||7.6||+0.1||–1.2||23rd||27.0||63.7||low||42%|
|Macquarie Island (district 300)|
This statement has been prepared based on information available at 10 am on Monday, 1 October 2007. 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.